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Effects of maternal hypoxia or nutrient restriction during pregnancy on endothelial function in adult male rat offspring
Abstract
Compromised fetal growth impairs vascular function; however, it is unclear whether chronic hypoxia in utero affects adult endothelial function. We hypothesized that maternal hypoxia (H, 12% O2, n= 9) or nutrient restriction (NR, 40% of control, n= 7) imposed from day 15-21 pregnancy in rats would impair endothelial function in adult male offspring (relative to control, C, n= 10). Using a wire myograph, endothelium-dependent relaxation in response to methacholine was assessed in small mesenteric arteries from 4- and 7-month-old (mo) male offspring. Nitric oxide (NO) mediation of endothelium-dependent relaxation was evaluated using N(omega)-nitro-L-arginine methyl ester (L-NAME; NO synthase inhibitor). Observed differences in the NO pathway at 7 months were investigated using exogenous superoxide dismutase (SOD) to reduce NO scavenging, and sodium nitroprusside (SNP; NO donor) to assess smooth muscle sensitivity to NO. Sensitivity to methacholine-induced endothelium-dependent relaxation was reduced in H offspring at 4 months (P < 0.05), but was not different among groups at 7 months. L-NAME reduced methacholine sensitivity in C (P < 0.01), H (P < 0.01) and NR (P < 0.05) offspring at 4 months, but at 7 months L-NAME reduced sensitivity in C (P < 0.05), tended to in NR (P= 0.055) but had no effect in H offspring. SOD did not alter sensitivity to methacholine in C, but increased sensitivity in H offspring (P < 0.01). SNP responses did not differ among groups. In summary, prenatal hypoxia, but not nutrient restriction impaired endothelium-dependent relaxation at 4 months, and reduced NO mediation of endothelial function at 7 months, in part through reduced NO bio-availability. Distinct effects following reduced maternal oxygen versus nutrition suggest that decreased oxygen supply during fetal life may specifically impact adult vascular function.
... Previous studies have reported that oxygen levels play a critical role in stem/progenitor cell-fate decisions and cardiac development [19,20,[38][39][40]. Non-physiological hypoxia, as a major challenge to fetuses during the gestation due to the reduction in oxygen delivery to the developing fetus, has been reported to increase the occurrence of congenital cardiac anomalies [8,35,39,41]. Thus, the role of hypoxia in regulation of CPC proliferation and differentiation for cardiac malformations has gained increasing attentions. ...
... Low oxygen levels have been reported to maintain self-renew and an undifferentiated state of stem cells and improve their proliferative capacity by activating canonical Wnt pathway signaling and PI3K/Akt pathway [43]. Prenatal hypoxia leads to an increase in cardiac vulnerability to cardiovascular dysfunction in later life through upregulation of Akt pathway [41,44]. A recent study has shown that short-term preconditioning of CPCs by hypoxia improves CPC proliferation and survival to enhance the cell function ex vivo [45]. ...
... As the first organ to form in the embryo, hearts fully develop during the later stages and function at birth. Exposure to 12% of hypoxic stress from E15 to E21 impairs rat offspring's vascular function in later life [41]. Hypoxic insult by 8% oxygen for 24 h causes a lethal rate of 89% of E13 fetuses, but 5% of E11.5 and 51% of E17.5 fetuses [46], indicating E13 is a very sensitive heart development stage. ...
Hypoxia is one of the most frequent and severe stresses to an organism’s homeostatic mechanisms, and hypoxia during gestation has profound adverse effects on the heart development increasing the occurrence of congenital heart defects (CHDs). Cardiac progenitor cells (CPCs) are responsible for early heart development and the later occurrence of heart disease. However, the mechanism of how hypoxic stress affects CPC fate decisions and contributes to CHDs remains a topic of debate. Here we examined the effect of hypoxic stress on the regulations of CPC fate decisions and the potential mechanism. We found that experimental induction of hypoxic responses compromised CPC function by regulating CPC proliferation and differentiation and restraining cardiomyocyte maturation. In addition, echocardiography indicated that fetal hypoxia reduced interventricular septum thickness at diastole and the ejection time, but increased the heart rate, in mouse young adult offspring with a gender-related difference. Further study revealed that hypoxia upregulated microRNA-210 expression in Sca-1+ CPCs and impeded the cell differentiation. Blockage of microRNA-210 with LNA-anti-microRNA-210 significantly promoted differentiation of Sca-1+ CPCs into cardiomyocytes. Thus, the present findings provide clear evidence that hypoxia alters CPC fate decisions and reveal a novel mechanism of microRNA-210 in the hypoxic effect, raising the possibility of microRNA-210 as a potential therapeutic target for heart disease.
... Mesenteric arteries (MA, intra lumen 100-500um) are the most typical resistance arteries that play important roles in BP [16]. Previous experiments using adult offspring born from mothers with normal BP and hypoxia in pregnancy have demonstrated MA impairments such as augmented vasoconstrictions to vascular agonists [17], endothelial dysfunction [18], and aggravated arterial stiffness [19]. However, there has been very limited information regarding effects and mechanisms of prenatal hypoxia on vascular functions and BP in adolescent offspring with genetic defects. ...
... Vascular tone and peripheral vascular resistance are major determinants of arterial pressure as well as for development of hypertension. In normal BP mothers, such as Sprague-Dawley rats, peripheral vascular dysfunction of offspring induced by prenatal negative stimulus was extensively studied [17][18][19][20][21]. Notably, accumulating evidences have suggested a relationship between prenatal hypoxia and increased cardiovascular risks in postnatal life in adults, which could be attributed to anomalous vascular tone [36]. ...
... Vascular vasodilatation plays important roles in the pathophysiology of hypertension. Previous studies showed a remarkably impaired vasodilatation in mesenteric arteries in normal BP rodents exposure to prenatal hypoxia [18,37]. In the present study, endothelium-dependent and independent relaxations were assessed respectively. ...
Prenatal hypoxia can induce cardiovascular diseases in the offspring. This study determined whether and how prenatal hypoxia may cause malignant hypertension and impaired vascular functions in spontaneous hypertension rat (SHR) offspring at adolescent stage. Pregnant SHR were placed in a hypoxic chamber (11% O2) or normal environment (21% O2) from gestational day 6 until birth. Body weight and blood pressure (BP) of SHR offspring were measured every week from 5 weeks old. Mesenteric arteries were tested. Gestational hypoxia resulted in growth restriction during 6–12 weeks and a significant elevation in systolic pressure in adolescent offspring at 12 weeks old. Notably, endothelial vasodilatation of mesenteric arteries was impaired in SHR adolescent offspring exposed to prenatal hypoxia, vascular responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were reduced, as well as plasma nitric oxide levels and expression of endothelial nitric oxide synthase (eNOS) in vessels were decreased. Moreover, mesenteric arteries in SHR offspring following prenatal hypoxia showed enhanced constriction responses to phenylephrine (PE), associated with up-regulated activities of L-type calcium channel (Ca²⁺-dependent), RhoA/Rock pathway signaling (Ca²⁺-sensitization), and intracellular Ca²⁺ flow. Pressurized myograph demonstrated altered mechanical properties with aggravated stiffness in vessels, while histological analysis revealed vascular structural disorganization in prenatal hypoxia offspring. The results demonstrated that blood pressure and vascular function in young SHR offspring were affected by prenatal hypoxia, providing new information on development of hypertension in adolescent offspring with inherited hypertensive backgrounds.
... Other adverse conditions that induce fetal hypoxia include pregnancy at high altitude [13][14][15][16], maternal smoking [17], maternal respiratory diseases and severe anaemia [18,19]. Prenatal hypoxia has been shown in causing vascular dysfunction in the offspring, characterized by increased myogenic tone of mesenteric arteries (MAs), impaired NOdependent relaxation in resistance vessels, and increased microvascular stiffness [20][21][22][23]. However, the mechanisms underlying vascular dysfunction in the offspring by prenatal hypoxia was not fully understood, especially the knowledge of the ion channel functions in resistance arteries is limited. ...
... The control rats were treated with the same conditions except chambers filled with room air. All pups were weighed after birth, 8 pups per dam were randomly selected and used for the experiments [21]. ...
... Peroxynitrite (ONOOformed in tissue by the nonenzymatic interaction between superoxide anion and nitric oxide (NO), could inhibit VSMCs BK channels [53]. In addition, hypoxia during late gestation reduced NO-mediated endothelial functions in rat offspring [21]. To clarify the effects of prenatal hypoxia on BK channel functions in MASMCs, vascular functions were tested in MAs with L-NAME (NO synthase inhibitor). ...
Background/aims:
Chronic hypoxia in utero could impair vascular functions in the offspring, underlying mechanisms are unclear. This study investigated functional alteration in large-conductance Ca2+-activated K+ (BK) channels in offspring mesenteric arteries following prenatal hypoxia.
Methods:
Pregnant rats were exposed to normoxic control (21% O2, Con) or hypoxic (10.5% O2, Hy) conditions from gestational day 5 to 21, their 7-month-old adult male offspring were tested for blood pressure, vascular BK channel functions and expression using patch clamp and wire myograh technique, western blotting, and qRT-PCR.
Results:
Prenatal hypoxia increased pressor responses and vasoconstrictions to phenylephrine in the offspring. Whole-cell currents density of BK channels and amplitude of spontaneous transient outward currents (STOCs), not the frequency, were significantly reduced in Hy vascular myocytes. The sensitivity of BK channels to voltage, Ca2+, and tamoxifen were reduced in Hy myocytes, whereas the number of channels per patch and the single-channel conductance were unchanged. Prenatal hypoxia impaired NS1102- and tamoxifen-mediated relaxation in mesenteric arteries precontracted with phenylephrine in the presence of Nω-nitro-L-arginine methyl ester. The mRNA and protein expression of BK channel β1, not the α-subunit, was decreased in Hy mesenteric arteries.
Conclusions:
Impaired BK channel β1-subunits in vascular smooth muscle cells contributed to vascular dysfunction in the offspring exposed to prenatal hypoxia.
... As a result, basal production of NO has been shown to be decreased in the aorta (124,331) and pulmonary arteries (342). In other studies, eNOS expression was unaltered: aortic or renal beds from offspring of Japanese macaques fed a high-fat diet (117), in cerebral (208) or in mesenteric arteries of rats exposed to maternal hypoxia (432). Expression levels alone, however, do not provide information on the functionality of the enzyme. ...
... C) PROSTAGLANDINS. The involvement of prostaglandins (FIG-URE 3) in mediating vasodilation is often relatively minor (266,432); however, developmental programming has been shown to further reduce its involvement in mesenteric artery vasodilation in male offspring of protein-restricted (405) or vascular tone in male offspring of hypoxic (166) rats. This may be a result of reduced receptor expression since a study by Van Huyen et al. (413) demonstrated reduced vasodilation that was a result of reduced prostacyclin receptor expression. ...
... Since anti-inflammatory treatment with sulfasalazine was unable to ameliorate this increase, it is possible that this was a result of a compensatory vascular increase in the production of prostaglandins rather than an excess inflammatory response. Conversely, a study by Williams et al. (432) found that mesenteric arteries in adult offspring of hypoxic dams had an increased prostaglandinmediated vasoconstrictor response. Furthermore, acute hypoxia (gestational day 19 -21) combined with cyclooxygenase inhibition caused right ventricle hypertrophy, pulmonary artery remodeling, and increased vascular eNOS expression (445), suggesting that a reduction of prostaglandins in utero might lead to the development of pulmonary hypertension. ...
The developmental origins of health and disease theory is based on evidence that a suboptimal environment during fetal and neonatal development can significantly impact the evolution of adult-onset disease. Abundant evidence exists that a compromised prenatal (and early postnatal) environment leads to an increased risk of hypertension later in life. Hypertension is a silent, chronic, and progressive disease defined by elevated blood pressure (>140/90 mmHg) and is strongly correlated with cardiovascular morbidity/ mortality. The pathophysiological mechanisms, however, are complex and poorly understood, and hypertension continues to be one of the most resilient health problems in modern society. Research into the programming of hypertension has proposed pharmacological treatment strategies to reverse and/or prevent disease. In addition, modifications to the lifestyle of pregnant women might impart far-reaching benefits to the health of their children. As more information is discovered, more successful management of hypertension can be expected to follow; however, while pregnancy complications such as fetal growth restriction, preeclampsia, preterm birth, etc., continue to occur, their offspring will be at increased risk for hypertension. This article reviews the current knowledge surrounding the developmental origins of hypertension, with a focus on mechanistic pathways and targets for therapeutic and pharmacologic interventions.
... This model of intrauterine stress induced by long-term hypoxia deprives the fetus of oxygen vital for proper development. Maternal food intake is also reduced potentially causing another developmental programming effect [69,[71][72]. Epidemiological studies indicate that in utero insults influence endothelial function in fetal life [73], children [74], or young adults [75]. Experimental models of prenatal hypoxia support these observations noted in low birth weight individuals via a mechanism that involves impairment in the nitric oxide system [71]. ...
... Epidemiological studies indicate that in utero insults influence endothelial function in fetal life [73], children [74], or young adults [75]. Experimental models of prenatal hypoxia support these observations noted in low birth weight individuals via a mechanism that involves impairment in the nitric oxide system [71]. Studies by Williams et al. demonstrated that prenatal hypoxia programmed premature aging of vasculature in IUGR male offspring [69,71] whereas Morton et al. demonstrated that female IUGR offspring exhibited a loss of NO-induced vasodilation that occurred at a later age than male IUGR [70]. ...
... Experimental models of prenatal hypoxia support these observations noted in low birth weight individuals via a mechanism that involves impairment in the nitric oxide system [71]. Studies by Williams et al. demonstrated that prenatal hypoxia programmed premature aging of vasculature in IUGR male offspring [69,71] whereas Morton et al. demonstrated that female IUGR offspring exhibited a loss of NO-induced vasodilation that occurred at a later age than male IUGR [70]. To further examine the sex difference in the developmental programming of CV risk Bourque et al. investigated vascular reactivity to endothelin-1 (ET-1), a potent vasoconstrictor [76]. ...
Hypertension is a risk factor for cardiovascular disease, the leading cause of death worldwide. Although multiple factors contribute to the pathogenesis of hypertension, studies by Dr David Barker reporting an inverse relationship between birth weight and blood pressure led to the hypothesis that slow growth during fetal life increased blood pressure and the risk for cardiovascular disease in later life. It is now recognized that growth during infancy and childhood, in addition to exposure to adverse influences during fetal life, contributes to the developmental programming of increased cardiovascular risk. Numerous epidemiological studies support the link between influences during early life and later cardiovascular health; experimental models provide proof of principle and indicate that numerous mechanisms contribute to the developmental origins of chronic disease. Sex has an impact on the severity of cardiovascular risk in experimental models of developmental insult. Yet, few studies examine the influence of sex on blood pressure and cardiovascular health in low-birth weight men and women. Fewer still assess the impact of ageing on sex differences in programmed cardiovascular risk. Thus, the aim of the present review is to highlight current data about sex differences in the developmental programming of blood pressure and cardiovascular disease.
... Maternal exposure to hypoxia can decrease maternal food intake. [32][33][34][35] Therefore, our experimental design included a subset of additional Funding information British Heart Foundation further showed enhanced mesenteric vasoconstrictor reactivity to phenylephrine and the thromboxane mimetic U46619. The effects of hypoxic pregnancy on cardiovascular remodelling and function in the fetal and adult offspring were independent of hypoxia-induced reductions in maternal food intake. ...
... Maternal exposure to 10% O 2 isobaric hypoxia can decrease maternal food intake. 34,35 Therefore, an additional n = 30 dams underwent pregnancy under normoxic conditions but were pair-fed (PF) to the daily amount consumed by hypoxic dams from day 15 of gestation. Half of them received melatonin treatment (PFM) and n = 7 per group were reserved for studies at the end of gestation, and n = 8 per group were reserved for studies in the adult offspring at 4 months of age. ...
Adopting an integrative approach, by combining studies of cardiovascular function with those at cellular and molecular levels, this study investigated whether maternal treatment with melatonin protects against programmed cardiovascular dysfunction in the offspring using an established rodent model of hypoxic pregnancy. Wistar rats were divided into normoxic (N) or hypoxic (H, 10% O2) pregnancy ± melatonin (M) treatment (5 μg·ml‐1.day‐1) in the maternal drinking water. Hypoxia ± melatonin treatment was from day 15‐20 of gestation (term is ca. 22 days). To control for possible effects of maternal hypoxia‐induced reductions in maternal food intake, additional dams underwent pregnancy under normoxic conditions but were pair‐fed (PF) to the daily amount consumed by hypoxic dams from day 15 of gestation. In one cohort of animals from each experimental group (N, NM, H, HM, PF, PFM) measurements were made at the end of gestation. In another, following delivery of the offspring, investigations were made at adulthood. In both fetal and adult offspring, fixed aorta and hearts were studied stereologically and frozen hearts were processed for molecular studies. In adult offspring, mesenteric vessels were isolated and vascular reactivity determined by in vitro wire myography. Melatonin treatment during normoxic, hypoxic or pair‐fed pregnancy elevated circulating plasma melatonin in the pregnant dam and fetus. Relative to normoxic pregnancy, hypoxic pregnancy increased fetal haematocrit, promoted asymmetric fetal growth restriction, and resulted in accelerated post‐natal catch‐up growth. While fetal offspring of hypoxic pregnancy showed aortic wall thickening, adult offspring of hypoxic pregnancy showed dilated cardiomyopathy. Similarly, while cardiac protein expression of eNOS was downregulated in the fetal heart, eNOS protein expression was elevated in the heart of adult offspring of hypoxic pregnancy. Adult offspring of hypoxic pregnancy further showed enhanced mesenteric vasoconstrictor reactivity to phenylephrine and the thromboxane mimetic U46619. The effects of hypoxic pregnancy on cardiovascular remodelling and function in the fetal and adult offspring were independent of hypoxia‐induced reductions in maternal food intake. Conversely, the effects of hypoxic pregnancy on fetal and postanal growth were similar in pair‐fed pregnancies. While maternal treatment of normoxic or pair‐fed pregnancies with melatonin on the offspring cardiovascular system was unremarkable, treatment of hypoxic pregnancies with melatonin in doses lower than those recommended for overcoming jet lag in humans enhanced fetal cardiac eNOS expression and prevented all alterations in cardiovascular structure and function in fetal and adult offspring. Therefore, the data support that melatonin is a potential therapeutic target for clinical intervention against developmental origins of cardiovascular dysfunction in pregnancy complicated by chronic fetal hypoxia.
... [16][17][18] Such studies, together with ours, have used several techniques to induce chronic fetal hypoxia, including hypoxic chambers, 17,[19][20][21] uterine artery blood flow restriction, 16,22 placental embolization, 23,24 umbilical artery ligation, 25 carunclectomy, 26 and exposure to high altitude. [27][28][29] Methods such as uterine artery restriction, placental embolization, or umbilical artery ligation will also reduce nutrient transfer to the fetus, and pregnant mammals placed in hypoxic chambers sometimes show reduced food intake, [30][31][32] although this is not always the case. 20,33 Some studies have attempted to control for hypoxia-induced reductions in maternal food intake by using a separate group of pair-fed animals. ...
... As an example, in rats, hypoxic pregnancy from days 15 to 21 of gestation (term is ≈21 days), reducing the O 2 to 12%, promotes significant fetal growth restriction and programmes cardiovascular dysfunction in the adult offspring. 30 Conversely, in rat pregnancy, hypoxic pregnancy from days 6 to 20 of gestation, reducing O 2 to 13%, has no effect on fetal growth but still programmes cardiovascular dysfunction in the adult offspring. 20,60 Data in the present study show that blocking basal NO production by administration of L-NAME caused a smaller increase in arterial blood pressure in chickens, which developed under hypoxic conditions. ...
In mammals, pregnancy complicated by chronic hypoxia can program hypertension in the adult offspring. However, mechanisms remain uncertain because the partial contributions of the challenge on the placenta, mother, and fetus are difficult to disentangle. Here, we used chronic hypoxia in the chicken embryo-an established model system that permits isolation of the direct effects of developmental hypoxia on the cardiovascular system of the offspring, independent of additional effects on the mother or the placenta. Fertilized chicken eggs were exposed to normoxia (N; 21% O2) or hypoxia (H; 13.5%-14% O2) from the start of incubation (day 0) until day 19 (hatching, ≈day 21). Following hatching, all birds were maintained under normoxic conditions until ≈6 months of adulthood. Hypoxic incubation increased hematocrit (+27%) in the chicken embryo and induced asymmetrical growth restriction (body weight, -8.6%; biparietal diameter/body weight ratio, +7.5%) in the hatchlings (all P<0.05). At adulthood (181±4 days), chickens from hypoxic incubations remained smaller (body weight, -7.5%) and showed reduced basal and stimulated in vivo NO bioavailability (pressor response to NG-nitro-L-arginine methyl ester, -43%; phenylephrine pressor response during NO blockade, -61%) with significant hypertension (mean arterial blood pressure, +18%), increased cardiac work (ejection fraction, +12%; fractional shortening, +25%; enhanced baroreflex gain, +456%), and left ventricular wall thickening (left ventricular wall volume, +36%; all P<0.05). Therefore, we show that chronic hypoxia can act directly on a developing embryo to program hypertension, cardiovascular dysfunction, and cardiac wall remodeling in adulthood in the absence of any maternal or placental effects.
... Chronic intrauterine hypoxia exposure is also associated with vascular structural and functional changes long-term. For instance, we have demonstrated increased expression of collagen type I and III fibers, altered ß/α myosin heavy chains ratio (ß/αMHC), decreased expression of matrix metalloproteinase 2, and impaired endothelial function in mesenteric arteries of adult rats exposed to hypoxia before birth (Morton, Rueda-Clausen, & Davidge, 2010;Williams, Hemmings, Mitchell, McMillen, & Davidge, 2005). The timing of development of these myocardial and vascular changes and the mechanisms responsible remain poorly defined. ...
... The aims of the current study, which utilized a previously defined rat model of prenatal hypoxia exposure (Morton et al., 2010Rueda-Clausen et al., 2009, 2011Williams et al., 2005;Xu et al., 2006), were to determine if left ventricular (LV) systolic or diastolic dysfunction and increased aortic stiffness are present in early postnatal life following Conclusion: Chronic fetal hypoxia is associated with progressive LV diastolic dysfunction, which corresponds with changes in nuclear shape and collagen fiber thickness, and increased aortic stiffness from early postnatal stages. ...
Aim:
We sought to explore whether fetal hypoxia exposure, an insult of placental insufficiency, is associated with left ventricular dysfunction and increased aortic stiffness at early postnatal ages.
Methods:
Pregnant Sprague Dawley rats were exposed to hypoxic conditions (11.5% FiO2 ) from embryonic day E15-21 or normoxic conditions (controls). After delivery, left ventricular function and aortic pulse wave velocity (measure of aortic stiffness) were assessed longitudinally by echocardiography from day 1 through week 8. A mixed ANOVA with repeated measures was performed to compare findings between groups across time. Myocardial hematoxylin and eosin and picro-sirius staining were performed to evaluate myocyte nuclear shape and collagen fiber characteristics, respectively.
Results:
Systolic function parameters transiently increased following hypoxia exposure primarily at week 2 (p < .008). In contrast, diastolic dysfunction progressed following fetal hypoxia exposure beginning weeks 1-2 with lower early inflow Doppler velocities, and less of an increase in early to late inflow velocity ratios and annular and septal E'/A' tissue velocities compared to controls (p < .008). As further evidence of altered diastolic function, isovolumetric relaxation time was significantly shorter relative to the cardiac cycle following hypoxia exposure from week 1 onward (p < .008). Aortic stiffness was greater following hypoxia from day 1 through week 8 (p < .008, except week 4). Hypoxia exposure was also associated with altered nuclear shape at week 2 and increased collagen fiber thickness at week 4.
Conclusion:
Chronic fetal hypoxia is associated with progressive LV diastolic dysfunction, which corresponds with changes in nuclear shape and collagen fiber thickness, and increased aortic stiffness from early postnatal stages.
... Hypoxia is a common form of intrauterine stress, and the fetus may experience prolonged hypoxic stress under a variety of conditions, including pregnancy at high altitude, pregnancy with anemia, placental insufficiency, cord compression, preeclampsia, heart, lung and kidney disease, or with hemoglobinopathy. Previous studies have suggested a possible link between antenatal hypoxia and increased risk of cardiovascular disease in offspring [6][7][8][9][10][11][12][13][14][15][16] . Studies in rats have demonstrated that maternal hypoxia results in heightened cardiac vulnerability to ischemia and reperfusion injury in offspring 17-25 . ...
... Hypoxia is a common form of intrauterine stress, and the fetus may experience prolonged hypoxic stress under a variety of conditions, including pregnancy at high altitude, pregnancy with anemia, placental insufficiency, cord compression, preeclampsia, heart, lung and kidney disease, or with hemoglobinopathy. Previous studies have suggested a possible link between antenatal hypoxia and increased risk of cardiovascular disease in offspring [6][7][8][9][10][11][12][13][14][15][16] . Studies in rats have demonstrated that maternal hypoxia results in heightened cardiac vulnerability to ischemia and reperfusion injury in offspring [17][18][19][20][21][22][23][24][25] . ...
The molecular mechanism of antenatal hypoxia impacting on fetal heart development and elevated risk of heart disease of adult offspring is poorly understood. We present a dataset integrating DNA methylome and transcriptome analyses of antenatal hypoxia affecting rat fetal and adult offspring hearts to understand hypoxia-mediated epigenomic reprogramming of the heart development. We showed that antenatal hypoxia not only induced DNA methylomic and transcriptomic changes in the fetal hearts, but also had a delayed and lasting effect on the adult offspring hearts. Of interest, antenatal hypoxia induced opposite changes in DNA methylation patterns in fetal and adult hearts, with a hypermethylation in the fetus and a hypomethylation in the adult. An extensive preprocessing, quality assessment, and downstream data analyses were performed on the genomic dataset so that the research community may take advantage of the public resource. These dataset could be exploited as a comprehensive resource for understanding fetal hypoxia-mediated epigenetic reprogramming in the heart development and further developmental programming of heart vulnerability to disease later in life.
Figshare doi: https://doi.org/10.6084/m9.figshare.9948572
... Prenatal hypoxia in rats also led to vascular endothelial dysfunction in mesenteric arteries of adult offspring, involving an increase in vasoconstriction and a https://doi.org/10.1016/j.phrs.2018.05.006 Received 24 January 2018; Received in revised form 17 April 2018; Accepted 9 May 2018 reduction in both flow-mediated and nitric oxide (NO)-dependent vasorelaxation [7][8][9]. ...
... Following euthanization at 7 or 13 months of age, second-order mesenteric arteries were dissected and mounted on two 40 μm wires in a wire myograph system as described by Bridges et al. [21]. Using established protocols [7,9,22], constrictor responses to phenylephrine (PE, 0.01-100 μmol/L) were determined. Cumulative concentration response curves to methacholine (MCh, 0.0001-100 μmol/L) were performed to assess endothelium-dependent vasorelaxation. ...
Intrauterine growth restriction, a common consequence of prenatal hypoxia, is a leading cause of fetal morbidity and mortality with a significant impact on population health. Hypoxia may increase placental oxidative stress and lead to an abnormal release of placental-derived factors, which are emerging as potential contributors to developmental programming. Nanoparticle-linked drugs are emerging as a novel method to deliver therapeutics targeted to the placenta and avoid risking direct exposure to the fetus. We hypothesize that placental treatment with antioxidant MitoQ loaded onto nanoparticles (nMitoQ) will prevent the development of cardiovascular disease in offspring exposed to prenatal hypoxia. Pregnant rats were intravenously injected with saline or nMitoQ (125 μM) on gestational day (GD) 15 and exposed to either normoxia (21% O2) or hypoxia (11% O2) from GD15-21 (term: 22 days). In one set of animals, rats were euthanized on GD 21 to assess fetal body weight, placental weight and placental oxidative stress. In another set of animals, dams were allowed to give birth under normal atmospheric conditions (term: GD 22) and male and female offspring were assessed at 7 and 13 months of age for in vivo cardiac function (echocardiography) and vascular function (wire myography, mesenteric artery). Hypoxia increased oxidative stress in placentas of male and female fetuses, which was prevented by nMitoQ. 7-month-old male and female offspring exposed to prenatal hypoxia demonstrated cardiac diastolic dysfunction, of which nMitoQ improved only in 7-month-old female offspring. Vascular sensitivity to methacholine was reduced in 13-month-old female offspring exposed to prenatal hypoxia, while nMitoQ treatment improved vasorelaxation in both control and hypoxia exposed female offspring. Male 13-month-old offspring exposed to hypoxia showed an age-related decrease in vascular sensitivity to phenylephrine, which was prevented by nMitoQ. In summary, placental-targeted MitoQ treatment in utero has beneficial sex- and age-dependent effects on adult offspring cardiovascular function.
... Mesenteric arteries are typical systemic arteries that regulate peripheral resistance. 16 Several reports have demonstrated that prenatal hypoxia was associated with long-term alterations in mesenteric artery functions, characterized by enhanced myogenic tone, 17 reduced nitric oxide-mediated vasodilation, 18 and increased arterial wall stiffness. 19 Furthermore, K + channels (eg, large-conductance calcium-activated K + [BK] and voltage-gated K + [K V ] channels) are important in regulating membrane potential (E m ), and inhibition of those channels in VSMCs leads to E m depolarization and enhanced Ca 2+ influx via L-type voltagegated Ca 2+ (Cav1.2) channels and VSMC contractility. ...
... Litters were reduced to 8 male pups at birth. 18 After weaning (4 weeks), male offspring from each group (control, n=24; hypoxia, n=24) were randomly provided either normalsalt diets containing 1% NaCl or high-salt diets (HS diets) containing 8% NaCl. Then, 4 groups were created: control offspring receiving a normal-salt diet (CNS; n=12 from 12 litters), control offspring receiving an HS diet (CHS; n=12 from 12 litters), hypoxia offspring receiving a normal-salt diet (HNS; n=12 from 12 litters), and hypoxia offspring receiving an HS diet (HHS; n=12 from 12 litters). ...
Background:
Prenatal hypoxia is suggested to be associated with increased risks of hypertension in offspring. This study tested whether prenatal hypoxia resulted in salt-sensitive offspring and its related mechanisms of vascular ion channel remodeling.
Methods and results:
Pregnant rats were housed in a normoxic (21% O2) or hypoxic (10.5% O2) chamber from gestation days 5 to 21. A subset of male offspring received a high-salt diet (8% NaCl) from 4 to 12 weeks after birth. Blood pressure was significantly increased only in the salt-loading offspring exposed to prenatal hypoxia, not in the offspring that received regular diets and in control offspring provided with high-salt diets. In mesenteric artery myocytes from the salt-loading offspring with prenatal hypoxia, depolarized resting membrane potential was associated with decreased density of L-type voltage-gated Ca2+(Cav1.2) and voltage-gated K+channel currents and decreased calcium sensitive to the large-conductance Ca2+-activated K+channels. Protein expression of the L-type voltage-gated Ca2+α1C subunit, large-conductance calcium-activated K+channel (β1, not α subunits), and voltage-gated K+channel (KV2.1, not KV1.5 subunits) was also decreased in the arteries of salt-loading offspring with prenatal hypoxia.
Conclusions:
The results demonstrated that chronic prenatal hypoxia may program salt-sensitive hypertension in male offspring, providing new information of ion channel remodeling in hypertensive myocytes. This information paves the way for early prevention and treatments of salt-induced hypertension related to developmental problems in fetal origins.
... In summary, intrauterine undernutrition (Figure 1(a)), such as maintenance on a low-protein or hypocaloric diet in utero, induces IUGR that manifests as low birth weights [131]. A limited supply of substrates restricts fetal growth and delays cardiomyocyte binucleation [115,119]. ...
... A limited supply of substrates restricts fetal growth and delays cardiomyocyte binucleation [115,119]. Induced intrauterine hypoxia also induces IUGR and consequently low birth weights [131]. Low birth weights are associated with CVD later in life. ...
Programming with an insult or stimulus during critical developmental life stages shapes metabolic disease through divergent mechanisms. Cardiovascular disease increasingly contributes to global morbidity and mortality, and the heart as an insulin-sensitive organ may become insulin resistant, which manifests as micro- and/or macrovascular complications due to diabetic complications. Cardiogenesis is a sequential process during which the heart develops into a mature organ and is regulated by several cardiac-specific transcription factors. Disrupted cardiac insulin signalling contributes to cardiac insulin resistance. Intrauterine under- or overnutrition alters offspring cardiac structure and function, notably cardiac hypertrophy, systolic and diastolic dysfunction, and hypertension that precede the onset of cardiovascular disease. Optimal intrauterine nutrition and oxygen saturation are required for normal cardiac development in offspring and the maintenance of their cardiovascular physiology.
... Similarly, several studies including our own in mammalian experimental animal models have shown that maternal chronic hypoxia during pregnancy can lead to IUGR and programme increased cardiovascular risk in the offspring (Thompson & Weiner, 1999;Camm et al. 2010; Thompson et al. 2011;Giussani et al. 2012). However, because experimental induction of chronic hypoxia in rodents can reduce maternal food intake and/or alter the quality of the maternal milk (Williams et al. 2005b;Wlodek et al. 2005;O'Dowd et al. 2008;Camm et al. 2010), the contribution of chronic fetal hypoxia versus chronic fetal and/or neonatal under-nutrition under these conditions, again, remains uncertain. By using the chicken embryo as an animal model, science has been able to circumvent a number of these problems because, in contrast to mammals, with the exception of monotremes, in the chicken the effects of changes in oxygenation on the embryo can be isolated and determined directly, independent of changes in the maternal physiology. ...
... Aortic hypertrophy often precedes the clinical manifestation of hypertension, atherosclerosis and coronary heart disease (Arnett et al. 1994). Consequently, the remodelling of the heart and major vessels early in life due to suspected chronic fetal hypoxia may increase the risk of developing cardiovascular disease in adulthood (Williams et al. 2005b;Crispi et al. 2010;Giussani et al. 2012;Giussani & Davidge, 2013). ...
It is now established that adverse conditions during pregnancy can trigger a fetal origin of cardiovascular dysfunction and/or increase the risk of heart disease in later life. Sub-optimal environmental conditions during early life that may promote the development of cardiovascular dysfunction in the offspring include alterations in fetal oxygenation and nutrition as well as fetal exposure to stress hormones, such as glucocorticoids. There has been growing interest in identifying the partial contributions of each of these stressors to programming of cardiovascular dysfunction. However, in humans and in many animal models this is difficult, as the challenges cannot be disentangled. By using the chicken embryo as an animal model, science has been able to circumvent a number of problems. In contrast to mammals, in the chicken embryo the effects on the developing cardiovascular system of changes in oxygenation, nutrition or stress hormones can be isolated and determined directly, independent of changes in the maternal or placental physiology. In this review, we summarise studies that have exploited the chicken embryo model to determine the effects on prenatal growth, cardiovascular development and pituitary-adrenal function of isolated chronic developmental hypoxia. This article is protected by copyright. All rights reserved.
... 5 Other work has also showed that maternal hypoxia caused peripheral vascular damage in offspring rats. 19,21 The MCA is a critical pathway supplying oxygen and nutrition to the brain, and damage to a functional MCA would lead to central nervous diseases. 22 Because vascular wall thickness and diameters could be altered in vascular diseases, 23 we measured them in offspring. ...
... Previous studies had reported that hypoxia during pregnancy was harmful to the endothelium-dependent vasodilatation in pulmonary and mesenteric arteries. 19,21 The present study demonstrated that it damaged endothelial NO synthase in the MCA. AT2 receptor-induced vasodilatation depended on generation of NO via endothelial NO synthase. ...
Background
Hypoxia during pregnancy could cause abnormal development and lead to increased risks of vascular diseases in adults. This study determined angiotensin II (AII)‐mediated vascular dysfunction in offspring middle cerebral arteries (MCA).
Methods and Results
Pregnant rats were subjected to hypoxia. Vascular tension in offspring MCA by AII with or without inhibitors, calcium channel activities, and endoplasmic reticulum calcium stores were tested. Whole‐cell patch clamping was used to investigate voltage‐dependent calcium channel currents. mRNA expression was tested using quantitative real‐time polymerase chain reaction. AII‐mediated MCA constriction was greater in male offspring exposed to prenatal hypoxia. AT1 and AT2 receptors were involved in the altered AII‐mediated vasoconstriction. Prenatal hypoxia increased baseline activities of L‐type calcium channel currents in MCA smooth muscle cells. However, calcium currents stimulated by AII were not significantly changed, whereas nifedipine inhibited AII‐mediated vasoconstrictions in the MCA. Activities of IP3/ryanodine receptor–operated calcium channels, endoplasmic reticulum calcium stores, and sarcoendoplasmic reticulum membrane Ca²⁺‐ATPase were increased. Prenatal hypoxia also caused dysfunction of vasodilatation via the endothelium NO synthase. The mRNA expressions of AT1A, AT1B, AT2R, Cav1.2α1C, Cav3.2α1H, and ryanodine receptor RyR2 were increased in the prenatal‐hypoxia group.
Conclusions
Hypoxia in pregnancy could induce dysfunction in both contraction and dilation in the offspring MCA. AII‐increased constriction in the prenatal‐hypoxia group was not mainly dependent on the L‐type and T‐type calcium channels; it might predominantly rely on the AII receptors, IP3/ryanodine receptors, and the endoplasmic reticulum calcium store as well as calcium ATPase.
... Hypoxia represents a major threat to the developing fetus often accompanying situations such as intra-uterine growth restriction (IUGR), preeclampsia, smoking, high altitude and obesity [9][10][11][12][13][14][15][16]. In rodents, moderate sustained gestational hypoxia (ranging from 10-12% O 2 ) has been reported to program offspring for the development of both cardiovascular [17][18][19] and metabolic disorders [20,21]. Recently, moderate sustained gestational hypoxia (11.5% O 2 for the final six days of gestation) that resulted in IUGR pups in Sprague-Dawley (SD) rats was shown to increase abdominal adiposity and metabolic disorders (e.g. ...
... Previous studies reported decreased food intake and fetal weights in rodents in response to 10% hypoxia during gestation [17,19,21,34]. To assess the effect of our four day 12% O 2 gestational hypoxia paradigm on maternal food intake, SD dams (n = 5) were subjected to moderate hypoxia (12% O 2 ) starting at 0:800 h on day 15 through day 19. ...
The effect of gestational hypoxia on the neonatal leptin surge, development of hypothalamic arcuate nuclei (ARH) projections and appetite that could contribute to the programming of offspring obesity is lacking. We examined the effect of 12% O2 from gestational days 15–19 in the Sprague-Dawley rat on post-weaning appetite, fat deposition by MRI, adipose tissue cytokine expression, the neonatal leptin surge, ARH response to exogenous leptin, and αMSH projections to the paraventricular nucleus (PVN) in response to a high fat (HFD) or control diet (CD) in male offspring. Normoxia (NMX) and Hypoxia (HPX) offspring exhibited increased food intake when fed a HFD from 5–8 weeks post-birth; HPX offspring on the CD had increased food intake from weeks 5–7 vs. NMX offspring on a CD. HPX offspring on a HFD remained hyperphagic through 23 weeks. Body weight were the same between offspring from HPX vs. NMX dams from 4–12 weeks of age fed a CD or HFD. By 14–23 weeks of age, HPX offspring fed the CD or HFD as well as male NMX offspring fed the HFD were heavier vs. NMX offspring fed the CD. HPX offspring fed a CD exhibited increased abdominal adiposity (MRI) that was amplified by a HFD. HPX offspring fed a HFD exhibited the highest abdominal fat cytokine expression. HPX male offspring had higher plasma leptin from postnatal day (PN) 6 through 14 vs. NMX pups. HPX offspring exhibited increased basal c-Fos labeled cells in the ARH vs. NMX pups on PN16. Leptin increased c-Fos staining in the ARH in NMX but not HPX offspring at PN16. HPX offspring had fewer αMSH fibers in the PVN vs. NMX offspring on PN16. In conclusion, gestational hypoxia impacts the developing ARH resulting in hyperphagia contributing to adult obesity on a control diet and exacerbated by a HFD.
... The growth restriction and cardiac and aortic wall remodelling that develops in sea level chick embryos incubated at high altitude no longer occurs in sea level embryos incubated at high altitude with oxygen supplementation (Giussani et al., 2007, Salinas et al., 2010, underlying the direct but not necessarily linked effects of isolated chronic hypoxia on fetal growth and cardiovascular development. Growth restriction, aortic wall thickening, cardiac and vascular dysfunction have also been reported in the chronically hypoxic fetus of mammalian species, such as in sheep, rodents and guinea pigs (Alonso et al., 1989, Browne et al., 1997a, 1997b, Gilbert, 1998, Hemmings et al., 2005, Herrera et al., 2012a, Jacobs et al., 1988, Kamitomo et al., 1992, 1994, 2002, Kim et al., 2005, Onishi et al., 2004, Thompson, 2003, Thompson et al., 1999, 2000, Williams et al., 2005a, 2005b. Fetal aortic wall thickening is particularly relevant in the clinical setting, as increased large artery stiffness predicts cardiovascular risk in humans (McEniery and Wilkinson, 2005), being a key component in the development of hypertension, atherosclerosis and coronary heart disease (Arnett et al., 1994). ...
... Ruijtenbeek et al. (Ruijtenbeek et al., 2003b) first reported that isolated femoral arteries of adult chickens following hypoxic incubation were more sensitive to electrical stimulation and pharmacological stimulation of peri-arterial sympathetic nerves, while showing reduced NO-dependent vasorelaxation. The developmental induction of NO-dependent endothelial dysfunction in peripheral resistance circulations has now been confirmed in adult offspring of mammalian species by the groups of Davidge and Giussani , Williams et al., 2005b. Interestingly, two reports have shown a significant inverse relationship between low birth weight and endothelial dysfunction in children in the first decade of life and in early adulthood (Leeson et al., 1997(Leeson et al., , 2001. ...
Cardiovascular disease (CVD) is a major health concern globally, as it is the greatest cause of death, produces substantial long-term morbidity and brings enormous humanitarian and economic cost. No longer thought to result from a combination of genetic predisposition and an unhealthy adult lifestyle, CVD prevalence is rising rapidly in developing societies. Recent research has revealed how CVD risk can be set in early life, particularly as a result of an unbalanced maternal diet, materno-fetal exposure to excess glucocorticoids or reduced oxygenation, risks that are amplified across the lifecourse in terms of reduced compensatory responses to later challenges. Developmental challenges, transduced by the mother and the placenta, can be viewed as stressors of the developing offspring's physiological phenotype, even though they may operate within the normal range of the developmental environment. Such stressors induce integrated responses which modulate the offspring's cardiovascular phenotype to maximise potential later fitness but can increase CVD risk, especially with unhealthy lifestyle and ageing. More severe challenges disrupt development. We discuss the processes underlying the adaptive responses, with particular emphasis on the interaction between blood flow and tissue and organ growth, and the role of reactive oxygen species in mediating these effects. At the molecular level, epigenetic processes by which environmental stressors can affect gene expression and alter offspring phenotype without changing the fixed genetic sequence, are thought to underlie the adaptive processes.
... Independent studies have reported that chronic fetal hypoxia can program endothelial dysfunction in later life (7,28,49). Chronic fetal hypoxia, leading to a significant increase in fetal hematocrit, promotes fetal aortic wall thickening and increased oxidative stress in the fetal heart and vasculature by the end of gestation (28). ...
... Finally, data in the present study also show that hypoxic pregnancy or allopurinol treatment did not affect the pregnancy characteristics, birth weight, or body weight at 4 or 15 mo of age. Although several models of more severe (10%) hypoxic pregnancy in rodents in the last third of gestation do induce a decrease in birth weight (10,13,32,49), this rodent model of developmental hypoxia is different as it is milder (13%) and is early in onset, starting at d 6 of gestation. Because of the temporal pattern of placental growth during gestation (67), early onset hypoxic pregnancy permits placental compensation (68). ...
Aging and developmental programming are both associated with oxidative stress and endothelial dysfunction, suggesting common mechanistic origins. However, their interrelationship has been little explored. In a rodent model of programmed cardiovascular dysfunction we determined endothelial function and vascular telomere length in young (4 mo) and aged (15 mo) adult offspring of normoxic or hypoxic pregnancy with or without maternal antioxidant treatment. We show loss of endothelial function [maximal arterial relaxation to acetylcholine (71 ± 3 vs. 55 ± 3%) and increased vascular short telomere abundance (4.2-1.3 kb) 43.0 ± 1.5 vs. 55.1 ± 3.8%) in aged vs. young offspring of normoxic pregnancy (P < 0.05). Hypoxic pregnancy in young offspring accelerated endothelial dysfunction (maximal arterial relaxation to acetylcholine: 42 ± 1%, P < 0.05) but this was dissociated from increased vascular short telomere length abundance. Maternal allopurinol rescued maximal arterial relaxation to acetylcholine in aged offspring of normoxic or hypoxic pregnancy but not in young offspring of hypoxic pregnancy. Aged offspring of hypoxic allopurinol pregnancy compared with aged offspring of untreated hypoxic pregnancy had lower levels of short telomeres (vascular short telomere length abundance 35.1 ± 2.5 vs. 48.2 ± 2.6%) and of plasma proinflammatory chemokine (24.6 ± 2.8 vs. 36.8 ± 5.5 pg/ml, P < 0.05). These data provide evidence for divergence of mechanistic pathways mediating cardiovascular aging and developmental programming of cardiovascular disease, and aging being decelerated by antioxidants even prior to birth.
... MUN males and females showed reduced maximal responses to ACh. However, maximal relaxation was lower in MUN males, as shown by the significant interaction between group and sex, similar to what has been previously described in other rat models of fetal undernutrition 45]. We used the iliac artery, a vessel in which, like the aorta, vascular relaxation is NO-dependent [35]. ...
Fetal undernutrition predisposes to hypertension development. Since nitric oxide (NO) is a key factor in blood pressure control, we aimed to investigate the role of NO alterations in hypertension induced by fetal undernutrition in rats. Male and female offspring from dams exposed to undernutrition during the second half of gestation (MUN) were studied at 21 days (normotensive) and 6 months of age (hypertension developed only in males). In aorta, we analyzed total and phosphorylated endothelial NO synthase (eNOS, p-eNOS), 3-nitrotyrosine (3-NT), and Nrf2 (Western blot). In plasma we assessed L-arginine, asymmetric and symmetric dimethylarginine (ADMA, SDMA; LC-MS/MS), nitrates (NOx, Griess reaction), carbonyl groups, and lipid peroxidation (spectrophotometry). In iliac arteries, we studied superoxide anion production (DHE staining, confocal microscopy) and vasodilatation to acetylcholine (isometric tension). Twenty-one-day-old MUN offspring did not show alterations in vascular e-NOS or 3NT expression, plasma L-Arg/ADMA ratio, or NOx. Compared to control group, 6-month-old MUN rats showed increased aortic expression of p-eNOS/eNOS and 3-NT, being Nrf2 expression lower, elevated plasma L-arginine/ADMA, NOx and carbonyl levels, increased iliac artery DHE staining and reduced acetylcholine-mediated relaxations. These alterations in MUN rats were sex-dependent, affecting males. However, females showed some signs of endothelial dysfunction. We conclude that increased NO production in the context of a pro-oxidative environment, leads to vascular nitrosative damage and dysfunction, which can participate in hypertension development in MUN males. Females show a better adaptation, but signs of endothelial dysfunction, which can explain hypertension in ageing.
... 8 Data show that developmental hypoxia programmes in the adult offspring impaired NO-dependent endothelial function with increased sympathetic reactivity in peripheral arterioles, as well as sympathetically dominant regulation of cardiac function. 1,6,7,[9][10][11][12][13] These adverse outcomes of cardiovascular dysfunction precede the development of overt disease but are strongly implicated in the pathogenesis of future hypertension, atherosclerosis, and heart failure. [14][15][16] Therefore, their early diagnosis could help prevent further progression of dysfunction and the establishment of heart disease. ...
Work in preclinical animal models has established that pregnancy complicated by chronic fetal hypoxia and oxidative stress programmes cardiovascular dysfunction in adult offspring. Translating this to the human condition comes with challenges, including the early diagnosis of affected individuals to improve clinical outcomes. We hypothesize that components of programmed cardiovascular dysfunction in offspring can be identified in vivo via analysis of blood pressure variability and heart rate variability and that maternal treatment with the mitochondria-targeted antioxidant MitoQ is protective. Pregnant rats were exposed to normoxia or hypoxia (13% O 2 ) ±MitoQ (500 μM in water), from 6 to 20 days gestation. Offspring were maintained in normoxia postnatally. At 16 weeks of age, 1 male per litter was instrumented with vascular catheters and a femoral blood flow probe under isoflurane anesthesia. After recovery, arterial blood pressure and femoral flow were recorded in conscious, free-moving rats and analyzed. Offspring of hypoxic pregnancy had (1) increased very-low-frequency blood pressure variability (A) and heart rate variability (B), indices consistent with impaired endothelial function and (2) increased heart rate variability low/high-frequency ratio (C) and low-frequency blood pressure variability (D), indices of cardiac and vascular sympathetic hyperreactivity, respectively. MitoQ ameliorated A and B but not C and D. We show that asymptomatic cardiovascular dysfunction in adult offspring programmed by hypoxic pregnancy can be diagnosed in vivo by blood pressure variability and heart rate variability, suggesting that these noninvasive biomarkers could be translated to the clinical setting. MitoQ protected against programmed endothelial dysfunction but not sympathetic hyperreactivity, highlighting the divergent programming mechanisms involved.
... Offspring from women with PE have higher BP [7]. Experimental models that mimic the etiology of PE provide proof of principle and demonstrate sex-and age-specific differences in increased BP and CV risk in the IUGR offspring [49][50][51]; an observation also reported in offspring from human PE [9][10][11][12][13][14][15]18,52]. Yet, the origins of placental dysfunction, the critical mediator of poor fetal growth and the causative event in the in-utero programming of increased CV risk in the offspring, remains unclear. ...
Preeclampsia (PE), the leading cause of maternal and fetal morbidity and mortality, is associated with poor fetal growth, intrauterine growth restriction (IUGR) and low birth weight (LBW). Offspring of women who had PE are at increased risk for cardiovascular (CV) disease later in life. However, the exact etiology of PE is unknown. Moreover, there are no effective interventions to treat PE or alleviate IUGR and the developmental origins of chronic disease in the offspring. The placenta is critical to fetal growth and development. Epigenetic regulatory processes such as histone modifications, microRNAs and DNA methylation play an important role in placental development including contributions to the regulation of trophoblast invasion and remodeling of the spiral arteries. Epigenetic processes that lead to changes in placental gene expression in PE mediate downstream effects that contribute to the development of placenta dysfunction, a critical mediator in the onset of PE, impaired fetal growth and IUGR. Therefore, this review will focus on epigenetic processes that contribute to the pathogenesis of PE and IUGR. Understanding the epigenetic mechanisms that contribute to normal placental development and the initiating events in PE may lead to novel therapeutic targets in PE that improve fetal growth and mitigate increased CV risk in the offspring.
... Abnormal heart development and abnormal cardiovascular processes in the fetus can lead to congenital heart disease [1,2]. Studies have shown that chronic hypoxia in fetal stage can cause heart failure in the fetus and increase cardiovascular disease [3][4][5]. Therefore, early cardiac development of the fetus and the process of cardiovascular formation are significant. ...
Background:
Hypoxia causes oxidative stress and affects cardiovascular function and the programming of cardiovascular disease. Melatonin promotes antioxidant enzymes such as superoxide dismutase, glutathione reductase, glutathione peroxidase, and catalase.
Objectives:
This study aims to investigate the correlation between melatonin and hypoxia induction in cardiomyocytes differentiation.
Methods:
Mouse embryonic stem cells (mESCs) were induced to myocardial differentiation. To demonstrate the influence of melatonin under hypoxia, mESC was pretreated with melatonin and then cultured in hypoxic condition. The cardiac beating ratio of the mESC-derived cardiomyocytes, mRNA and protein expression levels were investigated.
Results:
Under hypoxic condition, the mRNA expression of cardiac-lineage markers (Brachyury, Tbx20, and cTn1) and melatonin receptor (Mtnr1a) was reduced. The mRNA expression of cTn1 and the beating ratio of mESCs increased when melatonin was treated simultaneously with hypoxia, compared to when only exposed to hypoxia. Hypoxia-inducible factor (HIF)-1α protein decreased with melatonin treatment under hypoxia, and Mtnr1a mRNA expression increased. When the cells were exposed to hypoxia with melatonin treatment, the protein expressions of phospho-extracellular signal-related kinase (p-ERK) and Bcl-2-associated X proteins (Bax) decreased, however, the levels of phospho-protein kinase B (p-Akt), phosphatidylinositol 3-kinase (PI3K), B-cell lymphoma 2 (Bcl-2) proteins, and antioxidant enzymes including Cu/Zn-SOD, Mn-SOD, and catalase were increased. Competitive melatonin receptor antagonist luzindole blocked the melatonin-induced effects.
Conclusions:
This study demonstrates that hypoxia inhibits cardiomyocytes differentiation and melatonin partially mitigates the adverse effect of hypoxia in myocardial differentiation by regulating apoptosis and oxidative stress through the p-AKT and PI3K pathway.
... Similar results have been reported in neonatal rat offspring exposed to prenatal hypoxia [154]. However, whether these functional changes persist beyond the neonatal period is not clear; although adult rat offspring exposed to prenatal hypoxia also exhibit impaired endothelial function [155][156][157], this could reflect an emergent pathology in adulthood, rather than the persistence of the perinatal phenotype. Interestingly, Leeson and colleagues reported changes in flow-mediated dilation in the brachial artery of low-birthweight children at 9-11 years of age, and these outcomes were evident in the absence of cardiovascular risk factors or other clinical complications [158]. ...
The developmental origins of health and disease (DOHaD) is a concept linking pre- and early postnatal exposures to environmental influences with long-term health outcomes and susceptibility to disease. It has provided a new perspective on the etiology and evolution of chronic disease risk, and as such is a classic example of a paradigm shift. What first emerged as the ‘fetal origins of disease’, the evolution of the DOHaD conceptual framework is a storied one in which preclinical studies played an important role. With its potential clinical applications of DOHaD, there is increasing desire to leverage this growing body of preclinical work to improve health outcomes in populations all over the world. In this review, we provide a perspective on the values and limitations of preclinical research, and the challenges that impede its translation. The review focuses largely on the developmental programming of cardiovascular function and begins with a brief discussion on the emergence of the ‘Barker hypothesis’, and its subsequent evolution into the more-encompassing DOHaD framework. We then discuss some fundamental pathophysiological processes by which developmental programming may occur, and attempt to define these as ‘instigator’ and ‘effector’ mechanisms, according to their role in early adversity. We conclude with a brief discussion of some notable challenges that hinder the translation of this preclinical work.
... demonstrated in middle cerebral arteries, 2 mesenteric arteries, [3][4][5][6] renal arteries 7,8 and femoral arteries. 9,10 More studies described increased blood pressure responses and greater vasoconstrictions of resistance arteries in the offspring exposed to prenatal hypoxia, [11][12][13] which were associated with altered vascular constrictor and dilator mechanisms. ...
As a common complication of pregnancy, gestational hypoxia has been shown to predispose offspring to vascular dysfunction. Propionate, one of short‐chain fatty acids, exerts cardioprotective effects via reducing blood pressure. This study examined whether prenatal hypoxia impaired propionate‐stimulated large‐conductance Ca2+‐activated K+ (BK) channel activities in vascular smooth muscle cells (VSMCs) of offspring. Pregnant rats were exposed to hypoxia (10.5% oxygen) and normoxia (21% oxygen) from gestational day 7‐21. At 6 weeks of age, VSMCs in mesenteric arteries of offspring were analysed for BK channel functions and gene expressions. It was shown firstly that propionate could open significantly BK single channel in VSMCs in a concentration‐dependent manner. Antagonists of G protein βγ subunits and inositol trisphosphate receptor could completely suppress the activation of BK by propionate, respectively. Gαi/o and ryanodine receptor were found to participate in the stimulation on BK. Compared to the control, vasodilation and increments of BK NPo (the open probability) evoked by propionate were weakened in the offspring by prenatal hypoxia with down‐regulated Gβγ and PLCβ. It was indicated that prenatal hypoxia inhibited propionate‐stimulated BK activities in mesenteric VSMCs of offspring via reducing expressions of Gβγ and PLCβ, in which endoplasmic reticulum calcium release might be involved.
... Various conditions can cause prolonged fetal stress of intrauterine hypoxia, including preeclampsia and placental insufficiency, pregnancy at high altitude, maternal anemia, and heart and lung disease, among others. Previous studies have suggested that antenatal hypoxia increases the risk of cardiovascular disease and heightened heart vulnerability to ischemia and reperfusion injury later in life [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. ...
Antenatal hypoxia caused epigenetic reprogramming of methylome and transcriptome in the developing heart and increased the risk of heart disease later in life. Herein, we investigated the impact of gestational hypoxia in proteome and metabolome in the hearts of fetus and adult offspring. Pregnant rats were treated with normoxia or hypoxia (10.5% O2) from day 15 to 21 of gestation. Hearts were isolated from near-term fetuses and 5 month-old offspring, and proteomics and metabolomics profiling was determined. The data demonstrated that antenatal hypoxia altered proteomics and metabolomics profiling in the heart, impacting energy metabolism, lipid metabolism, oxidative stress, and inflammation-related pathways in a developmental and sex dependent manner. Of importance, integrating multi-omics data of transcriptomics, proteomics, and metabolomics profiling revealed reprogramming of the mitochondrion, especially in two clusters: (a) the cluster associated with "mitochondrial translation"/"aminoacyl t-RNA biosynthesis"/"one-carbon pool of folate"/"DNA methylation"; and (b) the cluster with "mitochondrion"/"TCA cycle and respiratory electron transfer"/"acyl-CoA dehydrogenase"/"oxidative phosphorylation"/"complex I"/"troponin myosin cardiac complex". Our study provides a powerful means of multi-omics data integration and reveals new insights into phenotypic reprogramming of the mitochondrion in the developing heart by fetal hypoxia, contributing to an increase in the heart vulnerability to disease later in life.
... An association between low birth weight and early onset of essential arterial hypertension had first been postulated by Barker in the "fetal origins of adult disease hypothesis" [5,22,23]. Anemia causes a state of chronic hypoxia and two studies have further reported that this vasoconstrictor phenotype triggered by developmental hypoxia is not only present in fetal life but that chronic prenatal hypoxia can program permanent endothelial dysfunction in the resistance circulations of the adult offspring [24,25]. In the rat fetal offspring, on the day 20 of gestation, the aortic wall thickness was significantly increased in hypoxic pregnancy [26]. ...
Aims: In this study, we hypothesized that maternal anemia leads to altered expression of angiogenic proteins vascular endothelial growth factor (VEGF), placental growth factor (PLGF), nitrotyrosine (NT) residues, and endothelial nitric oxide synthase (e-NOS) in the placenta. Hence, we study the expression of the abovementioned proteins in the placentas of mothers with different grades of anemia.
Materials and methods: Our study was conducted in 48 pregnant women (36–40 weeks of gestation), who were divided into four groups—normal, mild, moderate, and severe anemia. After delivery, the expression of the angiogenic proteins was studied in their placentas by immunohistochemistry.
Results: In our study, 58.3% of the pregnant women were anemic, among which 20.83% had mild anemia, 18.75% had moderate anemia, and 18.75% had severe anemia. Immunohistochemical staining intensity for VEGF, PLGF, NT residues, and e-NOS proteins was observed to be higher in the placentas of anemic women when compared with the non-anemic women.
Conclusion: Our study showed that there is an increased expression of angiogenic proteins in the placentas of anemic mothers, which probably is an adaptive response leading to changes in placental vessels.
... Animal studies directly demonstrated that the maternal nutrient imbalance, such as nutrition restriction and overnutrition, results in hypertension, ventricular remodeling, and poor recovery from myocardial ischemia in offspring [26][27][28]. In endothelial cells, maternal chronic hypoxia or nutrient restriction during pregnancy impaired endothelial function in adult male rat offspring [29]. Another study further demonstrated that this maternal undernutrition-leaded endothelial dysfunction could not be revered by normal postnatal diet [30]. ...
Adult metabolic syndrome is considered to be elicited by the developmental programming which is regulated by the prenatal environment. The maternal excess intake of fructose, a wildly used food additive, is found to be associated with developmental programing-associated cardiovascular diseases. To investigate the effect of maternal fructose exposure (MFE) on endothelial function and repair, which participate in the initiation and progress of cardiovascular disease, we applied a rat model with maternal fructose excess intake during gestational and lactational stage and examined the number and function of endothelial progenitor cells (EPCs) in 3-month-old male offspring with induction of critical limb ischemia (CLI). Results showed that the circulating levels of c-Kit+/CD31+ and Sca-1+/KDR+ EPC were reduced by MFE. In vitro angiogenesis analysis indicated the angiogenic activity of bone marrow-derived EPC, including tube formation and cellular migration, was reduced by MFE. Western blots further indicated the phosphorylated levels of ERK1/2, p38-MAPK, and JNK in circulating peripheral blood mononuclear cells were up-regulated by MFE. Fourteen days after CLI, the reduced blood flow recovery, lowered capillary density, and increased fibrotic area in quadriceps were observed in offspring with MFE. Moreover, the aortic endothelium-mediated vasorelaxant response in offspring was impaired by MFE. In conclusion, maternal fructose intake during gestational and lactational stage modulates the number and angiogenic activity of EPCs and results in poor blood flow recovery after ischemic injury.
... The potential of fetal growth can be affected by a hostile uterine environment that may be associated with a chronic reduction of the oxygen and nutrient supplies and will eventually be reflected in a low estimated fetal weight (EFW) [1][2][3][4]. The fetal hemodynamic response to these conditions is adaptive in nature and prioritizes an optimal supply of oxygen to the brain, heart, and adrenal glands at the expense of muscle, bone, and fat tissue [5][6][7][8][9][10][11][12]. ...
Aim:
To determine whether Doppler evaluation at 20-24 weeks of gestation can predict reduced fetal size later in pregnancy or at birth.
Methods:
Fetal biometry and Doppler velocimetry were performed in 2,986 women with a singleton pregnancy at 20-24 weeks of gestation. Predictive performances of the umbilical artery pulsatility index (UA-PI) or the mean uterine artery pulsatility index (UtA-PI) >95th percentile, middle cerebral artery pulsatility index, or cerebroplacental ratio (CPR) <5th percentile for early small for gestational age (SGA; <34 weeks of gestation), late SGA (≥34 weeks of gestation), or SGA at birth (birthweight <10th percentile) were analyzed.
Results:
The prevalence of early SGA, late SGA, and SGA at birth was 1.1, 9.6, and 14.7%, respectively. A CPR <5th percentile had a positive likelihood ratio (LR+) of 8.2 (95% confidence interval [CI] 5.7-12.0) for early SGA, a LR+ of 1.6 (95% CI 1.1-1.2) for late SGA, and a LR+ of 1.9 (95% CI 1.4-2.6) for SGA at birth. A UtA-PI >95th percentile was associated with late SGA and SGA at birth, while an UA-PI >95th percentile was associated with early SGA. Associations were higher in fetuses with an estimated fetal weight <10th percentile.
Conclusion:
Fetal biometry and Doppler evaluation at 20-24 weeks of gestation can predict early and late SGA as well as SGA at birth.
... A common feature of IUGR is low oxygen availability/ hypoxia (5,9,26). Studies in our laboratory have shown that exposing pregnant rats to hypoxia [11-12% O 2 , gestational day (GD) [15][16][17][18][19][20][21] can lead to fetal growth restriction (24,28,34). Other laboratories have also demonstrated fetal growth restriction resulting from maternal hypoxia in rats (9% O 2 , GD 14.5-17.5), ...
Intrauterine growth restriction (IUGR) is a common pregnancy complication and is a leading cause of fetal morbidity and mortality. Placental hypoxia contributes to adverse fetal consequences, including IUGR. Exposing pregnant rats to hypoxia can lead to IUGR; however, assessment of maternal vascular function in a rat model of hypoxia, and the mechanisms that may contribute to adverse pregnancy outcomes, has not been extensively studied. We hypothesized that exposing pregnant rats to hypoxia will affect maternal systemic vascular function and increase the uterine artery resistance index (RI), which will be associated with IUGR. To test this hypothesis, pregnant rats were kept in normoxia (21% O2) or hypoxia (11% O2) from gestational day (GD) 6 to 20. Maternal blood pressure, utero-placental resistance index (RI) (ultrasound biomicroscopy) and vascular function (wire myography) were assessed in uterine and mesenteric arteries. Fetal weight was significantly reduced (P< 0.001), while maternal blood pressure was increased (P<0.05) in rats exposed to hypoxia. Maternal vascular function was also affected after exposure to hypoxia, including impaired endothelium-dependent vasodilation responses to methacholine (MCh) in isolated uterine arteries (pEC50 normoxia: 6.55±0.23 vs. hypoxia: 5.02±0.35, P<0.01) and a reduced uterine artery RI in vivo (normoxia: 0.63±0.04 vs. hypoxia: 0.53±0.01, P<0.05); associated with an increase in umbilical vein RI (normoxia: 0.35±0.02 vs. hypoxia: 0.45±0.04, P<0.05). These data demonstrate maternal and fetal alterations in vascular function due to prenatal exposure to hypoxia. Further, although there was a compensatory reduction in uterine artery RI in the hypoxia groups, this was not sufficient to prevent IUGR.
... Vascular endothelial cell play a pivotal role in CV system by producing a collection of vasoactive agents whose functions include vasodilatation, vasoconstriction, and vascular growth [86] . This axiom is confirmed by animal models in which fetal insult, which is induced by nutritional restriction, placental insufficiency or hypoxia, leads to vascular dysfunction due to the impairment of endothelium-dependent nitric oxide (NO) availability [87][88][89] . During hypoxia, an imbalance in potent vasoactive factors is generated and an increase in total peripheral resistance is programmed, thus contributing to the development of hypertension. ...
Nowadays metabolic syndrome represents a real outbreak affecting society. Paradoxically, pediatricians must feel involved in fighting this condition because of the latest evidences of developmental origins of adult diseases. Fetal programming occurs when the normal fetal development is disrupted by an abnormal insult applied to a critical point in intrauterine life. Placenta assumes a pivotal role in programming the fetal experience in utero due to the adaptive changes in structure and function. Pregnancy complications such as diabetes, intrauterine growth restriction, pre-eclampsia, and hypoxia are associated with placental dysfunction and programming. Many experimental studies have been conducted to explain the phenotypic consequences of fetal-placental perturbations that predispose to the genesis of metabolic syndrome, obesity, diabetes, hyperinsulinemia, hypertension, and cardiovascular disease in adulthood. In recent years, elucidating the mechanisms involved in such kind of process has become the challenge of scientific research. Oxidative stress may be the general underlying mechanism that links altered placental function to fetal programming. Maternal diabetes, prenatal hypoxic/ischaemic events, inflammatory/infective insults are specific triggers for an acute increase in free radicals generation. Early identification of fetuses and newborns at high risk of oxidative damage may be crucial to decrease infant and adult morbidity.
... In addition to activation of the sympathetic system, possible endothelial dysfunction 36 can explain increased BP induced by augmented conversion of inactive endothelin-1 to its active form in male rats. 37 It is well known that endothelial dysfunction is connected with hypertension 38 or BP and PP increase. ...
Decreased oxygenation during pregnancy and early periods of ontogeny can affect normal body development and result in diseases in adulthood. The aim of this study was to use the model of prenatal intermittent hypoxia (PIH) and evaluate the effects of short-term hypoxia at the end of gestation on blood pressure (BP) control in adulthood. Wistar rats were exposed daily to PIH for 4 h during gestational day 19 and 20. In adult male rats, heart rate (HR), systolic BP and pulse pressure (PP) were acquired by radiotelemetry during 1 week. On the basis of HR variability and BP variability, sympathovagal balance (LF/HF) and spontaneous baroreflex sensitivity (sBRS) were evaluated. Systolic BP and PP were significantly elevated in PIH rats in comparison with control rats during the light and dark phase of the day, while LF/HF increased only during the light phase of the day. In contrast, sBRS tended to decrease only during the dark phase in PIH rats. In all measured and calculated parameters, significant circadian rhythms were present and were not affected by PIH. In conclusion, our data suggest that short intermittent hypoxia at the end of gestation can increase BP and PP via significant changes in LF/HF, which occur especially during the passive phase of the day. Results suggest that minor changes in the autonomous nervous system activity induced by environmental conditions during the perinatal period may contribute to development of hypertension in adulthood.Hypertension Research advance online publication, 25 February 2016; doi:10.1038/hr.2016.21.
Background
Nitric oxide (NO) is the most important vasodilator secreted by vascular endothelial cells, and its abnormal synthesis is involved in the development of cardiovascular disease. The prenatal period is a critical time for development and largely determines lifelong vascular health in offspring. Given the high incidence and severity of gestational hypoxia in mid‐late pregnancy, it is urgent to further explore whether it affects the long‐term synthesis of NO in offspring vascular endothelial cells.
Methods and Results
Pregnant Sprague–Dawley rats were housed in a normoxic or hypoxic (10.5% O 2 ) chamber from gestation days 10 to 20. The thoracic aortas of fetal and adult male offspring were isolated for experiments. Gestational hypoxia significantly reduces the NO‐dependent vasodilation mediated by acetylcholine in both the fetal and adult offspring thoracic aorta rings. Meanwhile, acetylcholine‐induced NO synthesis is impaired in vascular endothelial cells from hypoxic offspring thoracic aortas. We demonstrate that gestational hypoxic offspring exhibit a reduced endothelial NO synthesis capacity, primarily due to increased expression of NADPH oxidase 2 and enhanced reactive oxygen species. Additionally, gestational hypoxic offspring show elevated levels of miR‐155‐5p in vascular endothelial cells, which is associated with increased expression of NADPH oxidase 2 and reactive oxygen species generation, as well as impaired NO synthesis.
Conclusions
The present study is the first to demonstrate that gestational hypoxia impairs endothelial NO synthesis via the miR‐155‐5p/NADPH oxidase 2/reactive oxygen species axis in offspring vessels. These novel findings indicate that the detrimental effects of gestational hypoxia on fetal vascular function can persist into adulthood, providing new insights into the development of vascular diseases.
Blood Oxidant Ties: The Evolving Concepts in Myocardial Injury and Cardiovascular Disease is an update on the recent advances in the development of antioxidant-based therapies. It starts with an overview of the mechanisms underlying the genesis of oxidative stress, summarizing the link between oxidative stress and a number of cardiovascular conditions. This is followed by an explanation of how oxidative stress interacts with lipid metabolism and the placental environment. Three chapters on the role of antioxidant-based therapy for cardiovascular diseases round up the book.
Key Features
- Outlines several cell-signaling pathways that are modulated by the interplay between reducing and oxidizing agents (redox status) and gene expression in the cardiovascular disease process
- Brings information about maternal programming environment in the placenta
- Covers development of novel nanotechnology-based antioxidant delivery systems for effective drug delivery
- Includes references for further reading
The book is aimed at a broad readership of scientific and medical professionals involved in research on cardiovascular diseases, pathophysiology, pharmacy, pharmaceutical science and life sciences. It also serves as a reference for scholars who want to understand the complex biochemical mechanisms of antioxidant agents.
For a long time it was assumed that the risk for diseases such as coronary heart disease (CHD) or insulin resistance, for example, develops from the genetic potential of the parents and is amplified by environmental influences such as an unfavorable lifestyle. This view has been completely overturned in the last two decades by the concept of fetal programming. The concept implies that a stimulus or insult during a sensitive period of fetal development produces permanent changes in structure, physiology, and metabolism, determining later risk for chronic diseases such as CHD and insulin resistance, as well as allergies, an impaired stress response, and many others in adulthood. The concept of Fetal Origins of Adult Disease (FOAD) was introduced by the British epidemiologist David Barker more than 20 years ago and has been the subject of intensive research ever since. The current research approaches aim to identify the biological mechanisms by which a prenatal stimulus or insult alters fetal development, the time lag between prenatal stimulus/insult and later disease, and the multiple factors that contribute to disease risk throughout the lifespan.
Intrauterine hypoxia-ischemia (HI) provides a strong stimulus for a developmental origin of both the central nervous system and cardiovascular diseases. This study aimed to investigate vascular functional and structural changes, oxidative stress damage, and behavioral alterations in adult male offspring submitted to HI during pregnancy. The pregnant Wistar rats had a uterine artery clamped for 45 min on the 18th gestational day, submitting the offspring to hypoxic-ischemic conditions. The Sham group passed to the same surgical procedure as the HI rats, without occlusion of the maternal uterine artery, and the controls consisted of non-manipulated healthy animals. After weaning, the male pups were divided into three groups: control, sham, and HI, according to the maternal procedure. At postnatal day 90 (P90), the adult male offspring performed the open field and forced swim tests. In P119, the rats had their blood pressure checked and were euthanized. Prenatal HI induced a depressive behavior in adult male offspring associated with a reduced vasodilator response to acetylcholine in perfused mesenteric arterial bed, and reduced superoxide dismutase and glutathione peroxidase activities in the aorta compared to control and sham groups. Prenatal HI also increased the vasoconstrictor response to norepinephrine, the media thickness, collagen deposition, and the oxidative damage in the aorta from adult male offspring compared to control and sham groups. Our results suggest an association among prenatal HI and adult vascular structural and functional changes, oxidative stress damage, and depressive behavior.
Premature birth results in an increased risk of respiratory distress and often requires oxygen therapy. While the supplemental oxygen has been implicated as a cause of bronchopulmonary dysplasia (BPD), in clinical practice this supplementation usually only occurs after the patient's oxygen saturation levels have dropped. The effect of hyperoxia on neonates has been extensively studied. However, there is an unanswered fundamental question: which has the most impact-hyperoxia, hypoxia or fluctuating oxygen levels? In this review, we will summarize the reported effect of hypoxia, hyperoxia or a fluctuation of oxygen levels (hypoxia/hyperoxia cycling) in preterm neonates, with special emphasis on the lungs.
Intrauterine growth restriction (IUGR) affects vascular reactivity in older rats, but at present the causative factors for this change are unknown. Therefore, we investigated downstream events associated with vascular reactivity, specifically, Ca2+-regulated force production and shifts in contractile protein content. The mesenteric artery from male and female 1-year-old Wistar-Kyoto rats was examined using two distinct experimental growth restriction models. Uterine ligation surgery restriction or a sham surgery was conducted at day 18 of pregnancy, whilst a food restriction diet (40% control diet) began on gestational day 15. Extracellular vascular reactivity was studied using intact mesenteric arteries, which were subsequently chemically permeabilized using 50 μM β-escin to examine Ca2+-activated force. Peak contractile responses to a K+-induced depolarization and phenylephrine were significantly elevated due to an increase in maximum Ca2+-activated force in the male surgery restricted group. No changes in contractile forces were reported between female experimental groups. Sections of mesenteric artery were examined using western blotting, revealing IUGR increased the relative abundance of the voltage-gated Ca2+ channel, inositol-1,4,5-trisphosphate receptor and myosin light chain kinase, in both male growth restricted groups, whereas no changes were seen in females. These findings demonstrate for the first time in 1-year-old rats that changes in vascular reactivity due to IUGR are caused by a change in Ca2+-activated force and shifts in important contractile protein content. These changes affect the Wistar-Kyoto rat in a sex-specific and maternal insult-dependent manner.
The worldwide increase in metabolic diseases has urged the scientific community to improve our understanding about the mechanisms underlying its cause and effects. A well supported area of studies had related maternal stress with early programming to the later metabolic diseases. Mechanisms upon origins of metabolic disturbances are not yet fully understood, even though stressful factors rising glucocorticoids have been put out as pivotal trigger by programming metabolic diseases as long-term consequence. Considering energy balance and glucose homeostasis, by producing and/or sensing regulator signals, hypothalamus-pituitary-adrenal axis and endocrine pancreas are directly affected by glucocorticoids excess. We focus on the evidences reporting the role of increased glucocorticoids due to perinatal insults on the physiological systems involved in the metabolic homeostasis and in the target organs such as endocrine pancreas, white adipose tissue and blood vessels. Besides, we review some mechanisms underlining the malprogramming of type 2 diabetes, obesity and hypertension. Studies on this field are currently ongoing and even there is a good understanding regarding the effects of glucocorticoids addressing metabolic diseases, few is known about the relationship between maternal insults rising glucocorticoids to pups' metabolic disturbances, a thorough understanding about that may provide pivotal clinical clues regarding those disorders.
Key points
Perinatal iron deficiency causes changes in offspring mesenteric artery function in adulthood, particularly in males, which can be exacerbated by chronic intake of a high salt diet.
Perinatal iron deficient male offspring exhibit enhanced conversion of big endothelin‐1 to active endothelin‐1, coinciding with decreased nitric oxide levels.
Perinatal iron deficient male offspring have reduced nitric oxide‐mediated endothelial‐dependent vasodilatation coincident with increased vascular superoxide levels following consumption of a high salt diet.
Perinatal iron deficiency has no apparent effects on vascular function in female offspring, even when fed a high salt diet.
These results help us better understand underlying vascular mechanisms contributing to increased cardiovascular risk from perinatal stressors such as iron deficiency.
Abstract
Pre‐ and immediate postnatal stressors, such as iron deficiency, can alter developmental trajectories and predispose offspring to long‐term cardiovascular dysfunction. Here, we investigated the impact of perinatal iron deficiency on vascular function in the adult offspring, and whether these long‐term effects were exacerbated by prolonged consumption of a high salt diet in adulthood. Female Sprague Dawley rats were fed either an iron‐restricted or ‐replete diet prior to and throughout pregnancy. Six weeks prior to experimentation at 6 months of age, adult offspring were fed either a normal or high salt diet. Mesenteric artery responses to vasodilators and vasoconstrictors were assessed ex vivo by wire myography. Male perinatal iron deficient offspring exhibited decreased reliance on nitric oxide with methacholine‐induced vasodilatation (interaction P = 0.03), coincident with increased superoxide levels when fed the high salt diet (P = 0.01). Male perinatal iron deficient offspring exhibit enhanced big endothelin‐1 conversion to active endothelin‐1 (P = 0.02) concomitant with decreased nitric oxide levels (P = 0.005). Female offspring vascular function was unaffected by perinatal iron deficiency, albeit the high salt diet was associated with impaired vasodilation and decreased nitric oxide production (P = 0.02), particularly in the perinatal iron deficient offspring. These findings implicate vascular dysfunction in the sex‐specific programming of cardiovascular dysfunction in the offspring by perinatal iron deficiency.
Perinatal sodium overload induces endothelial dysfunction in adult offspring, but the underlying mechanisms are not fully known. The involvement of tissue renin-angiotensin system on high sodium-programmed endothelial dysfunction was examined.
Acetylcholine and angiotensin I and II responses were analyzed in aorta and mesenteric resistance arteries from 24-week-old male offspring of normal-salt (O-NS, 1.3% NaCl) and high-salt (O-HS, 8% NaCl) fed dams. COX-2 expression, O2– production and angiotensin converting enzyme (ACE) activity were determined. A separated O-HS was treated with losartan (15 mg kg⁻¹/day) for eight weeks.
Compared to O-NS, O-HS were normotensive. Acetylcholine-induced relaxation was impaired in O-HS arteries, which was improved by tempol, apocynin or indomethacin. The angiotensin I-induced contraction was greater in O-HS arteries, whereas the angiotensin II responses were unchanged. ACE activity, O2– production and COX-2 expression were increased in O-HS arteries. In this group, the increased O2– production was inhibited by apocynin or losartan. Chronic losartan decreased COX-2 expression and restored the endothelium-dependent vasodilation in O-HS.
Our findings reiterate that perinatal sodium overload programs endothelial dysfunction in adult offspring through a blood pressure-independent mechanism. Our results also suggest that vascular angiotensin II is the main mediator of high sodium-programmed endothelial dysfunction, promoting COX-2 expression and oxidative stress.
Prenatal hypoxia can affect vascular functions in young offspring. However, there is limited knowledge regarding whether and how prenatal hypoxia influences vascular functions in aged offspring. This study compared the effects of prenatal hypoxia on the mesenteric arteries (MA) between a young adult and aged offspring and investigated the underlying mechanisms. Pregnant rats were randomly divided into the control and prenatal hypoxia groups. The vascular functions and molecular levels were assessed in 5-month-old (5 M) or 20-month-old (20 M) offspring. Prenatal hypoxia decreased acetylcholine-mediated vascular relaxations in 20-M but not 5-M offspring. Sodium nitroprusside-mediated relaxation curves were not altered by prenatal hypoxia in 5- and 20-M offspring. Prenatal hypoxia enhanced the contractile responses caused by phenylephrine, phorbol 12,13-dibutyrate, and 5-hydroxytryptamine only in 5-M offspring. The endothelial NO synthase (eNOS) activities were decreased along with downregulated eNOS mRNA expression and phosphorylated eNOS/total eNOS protein expression in 20-M offspring with prenatal hypoxia. The NADPH oxidase (NOX) inhibitor apocynin and superoxide dismutase (SOD) mimetic tempol restored the acetylcholine-mediated weaker relaxations in 20-M offspring with prenatal hypoxia. Enzyme-linked immunosorbent and dihydroethidium assay showed that prenatal hypoxia enhanced oxidative stress in 20-M offspring. Transmission electron microscopy showed that prenatal hypoxia damaged mitochondrial structures in the MA endothelial cells of 20-M offspring. Increased NOX2 protein expression and decreased SOD3 expression were found in 20-M offspring. The results demonstrated that endothelial dysfunction induced by intrauterine hypoxia occurred with aging via enhanced oxidative stress and decreased nitric oxide activities in aged offspring.
Intrauterine growth restriction (IUGR) is known to alter vascular smooth muscle reactivity, but it is currently unknown whether these changes are driven by downstream events that lead to force development, specifically, Ca²⁺‐regulated activation of the contractile apparatus or a shift in contractile protein content. This study investigated the effects of IUGR on Ca²⁺‐activated force production, contractile protein expression, and a potential phenotypic switch in the resistance mesenteric artery of both male and female Wistar‐Kyoto (WKY) rats following two different growth restriction models. Pregnant female WKY rats were randomly assigned to either a control (C; N = 9) or food restriction diet (FR; 40% of control; N = 11) at gestational day‐15 or underwent a bilateral uterine vessel ligation surgery restriction (SR; N = 10) or a sham surgery control model (SC; N = 12) on day‐18 of gestation. At 6‐months of age, vascular responsiveness of intact mesenteric arteries was studied, before chemically permeabilization using 50 μmol/L β‐escin to investigate Ca²⁺‐activated force. Peak responsiveness to a K⁺‐induced depolarization was decreased (P ≤ 0.05) due to a reduction in maximum Ca²⁺‐activated force (P ≤ 0.05) in both male growth restricted experimental groups. Vascular responsiveness was unchanged between female experimental groups. Segments of mesenteric artery were analyzed using Western blotting revealed IUGR reduced the relative abundance of important receptor and contractile proteins in male growth restricted rats (P ≤ 0.05), suggesting a potential phenotypic switch, whilst no changes were observed in females. Results from this study suggest that IUGR alters the mesenteric artery reactivity due to a decrease in maximum Ca²⁺‐activated force, and likely contributed to by a reduction in contractile protein and receptor/channel content in 6‐month‐old male rats, while female WKY rats appear to be protected.
Cardiovascular diseases (CVD) are a leading cause of mortality worldwide. Despite recognizing the importance of risk factors in dictating CVD susceptibility and onset, patient treatment remains a challenging endeavor. Increasingly, the benefits of prevention and mitigation of risk factors earlier in life are being acknowledged. The developmental origins of health and disease posits that insults during specific periods of development can influence long-term health outcomes; this occurs because the developing organism is highly plastic, and hence vulnerable to environmental perturbations. By extension, targeted therapeutics instituted during critical periods of development may confer long-term protection, and thus reduce the risk of CVD in later life. This review provides a brief overview of models of developmental programming, and then discusses the impact of perinatal therapeutic interventions on long-term cardiovascular function in the offspring. The discussion focuses on bioactive food components, as well as pharmacological agents currently approved for use in pregnancy; in short, those agents most likely to be used in pregnancy and early childhood.
Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.
Lange Zeit wurde angenommen, dass sich das Risiko für Erkrankungen wie beispielsweise koronare Herzerkrankung (KHK) oder Insulinresistenz aus dem genetischen Potential der Eltern entwickelt und durch Umwelteinflüsse wie ein ungünstiger Lebensstil verstärkt wird. Diese Auffassung wurde in den letzten zwei Jahrzehnten durch das Konzept der fetalen Programmierung komplett überworfen. Das Konzept beinhaltet, dass ein Stimulus oder Insult während einer sensiblen Phase der fetalen Entwicklung bleibende Veränderungen der Struktur, Physiologie und des Metabolismus hervorruft und damit das spätere Risiko für chronische Erkrankungen wie KHK und Insulinresistenz, aber auch für Allergien, eine gestörte Stressantwort u. v. m. im Erwachsenenalter bestimmt. Das Konzept der Fetal Origins of Adult Disease (FOAD) wurde vor über 20 Jahren von dem britischen Epidemiologen David Barker vorgestellt und seitdem intensiv beforscht. Die Forschungsansätze zielen darauf ab, die biologischen Mechanismen zu erkennen, über die ein pränataler Stimulus oder Insult die fetale Entwicklung verändert, die Zeitspanne zwischen vorgeburtlichem Stimulus/Insult und späterer Krankheit zu erfassen und die zahlreichen Faktoren zu identifizieren, die ein Erkrankungsrisiko während der gesamten Lebensspanne mitbeeinflussen
Based on considerable epidemiologic and laboratory based experimental evidence, it is clear that the optimal conditions for fetal growth and development require an environment of maternal homeostasis and well-being, and with the mother’s ability to respond appropriately to a particular stress. In view of its association with increased morbidity and mortality, fetal growth restriction (FGR) is to be avoided at all costs. Chapter 14 presents the clinical aspects of one not uncommon stress, that of high altitude or other [causes of] long-term hypoxia (LTH). Because fetal growth critically depends upon adequate maternal oxygenation, in addition to residence at high altitude (>2500 m), FGR may be associated with conditions such as that of mothers who are moderate to heavy smokers or with cyanotic heart disease, lung disease, severe anemia, and other conditions that cause prolonged hypoxia (Giussani et al. 2001; Hutter et al. 2010; Longo 1984, 1987; Longo and Goyal 2014; Neerhof and Thaete 2008). The importance of oxygen for fetal physiology was a foundation for my research interests and the development of surgical approaches to directly investigate the fetus during pregnancy (methodology described in Yellon and Apostolakis 1994). The chapter reviews the development of ideas in terms of the many physiologic, biochemical, cellular, and molecular aspects of LTH for the fetus and newborn.
In his essay “On being the right size,” the British geneticist, biometrician, and popularizer of science John Burdon Sanderson (JBS) Haldane (1892–1964) theorized on and presented some mathematical analysis for the optimal size of various organisms. In addition to consideration of body mass, he included surface area, weight-bearing bone structure, respiratory and circulating mechanisms, and other features of comparative anatomy and physiology (Haldane 1927). His analysis extended from insects to birds to a number of mammals which varied in size from mice to the rhinoceros. Haldane concluded “… that for every type of animal there is an optimal size” (Haldane 1927). A number of studies have disclosed that even for the fetus development follows clearly defined mathematical principles (Roberts 1906; see below). Prior to full maturity, timely growth, both physical and mental, is one of the best indicators of a fully functional physiological system and health. As is appreciated, optimal growth of the embryo-fetus and its various organs is a complex process that is a function of genetic makeup, state of maternal health, the availability of nutrients and oxygen, as well as a multitude of growth factors and hormones of maternal, placental, and fetal origin. In addition, a host of environmental factors that influence epigenetic programming play vital roles in this process. These factors are associated with physiologic, biochemical, and molecular changes, most of which are only poorly understood (Cheek 1975; Timiras 1972; Winick 1972). From mid-century onward, considerable emphasis has been placed on the mechanisms of cell division and multiplication (hyperplasia) and cell enlargement with cytoplasmic growth (hypertrophy) that result in the deposition of new tissue and change in anatomical form (Cheek 1975; Cockburn 1988; Fowden 1989; Winick 1972; Winick and Noble 1965).
Human and animal studies indicate that obesity during pregnancy adversely impacts both maternal health and offspring phenotype predisposing them to chronic diseases later in life including obesity, dyslipidemia, type 2 diabetes mellitus, and hypertension. Effective interventions during human pregnancy and/or lactation are needed to improve both maternal and offspring health. This review addresses the relationship between adverse perinatal insults and its negative impact on offspring development and presents some maternal intervention studies such as diet modification, probiotic consumption, or maternal exercise, to prevent or alleviate the negative outcomes in both the mother and her child.
Prenatal hypoxia is associated with growth restriction and adverse cardiovascular outcomes. Here, we describe renal and cardiovascular outcomes in ageing mouse offspring prenatally exposed to hypoxia (12% O2) from embryonic day 14.5 until birth. At 12 months of age, both male and female offspring exposed to prenatal hypoxia had elevated mean arterial pressure. Glomerular number was reduced by 25% in hypoxia-exposed male, but not female, offspring and this was associated with increased urinary albumin excretion, glomerular hypertrophy and renal fibrosis. Hypoxia-exposed offspring of both sexes were more susceptible to salt-induced cardiac fibrosis, however, renal fibrosis was exacerbated by high salt in males only. In male but not female hypoxia-exposed offspring, renal renin mRNA was increased at weaning. By 12 months, renal renin mRNA expression and concentrations were elevated in both sexes. mRNA expression of At 1a R was also elevated in male hypoxia-exposed offspring at 12 months. These results demonstrate that prenatal hypoxia programs elevated blood pressure and exacerbates salt-induced cardiovascular and renal pathology in a sex specific manner. Given sex differences observed in RAS expression and nephron number, future studies may consider RAS blockade as a therapeutic target in this model.
Epidemiology formed the basis of 'the Barker hypothesis', the concept of 'developmental programming' and today's discipline of the Developmental Origins of Health and Disease (DOHaD). Animal experimentation provided proof of the underlying concepts, and continues to generate knowledge of underlying mechanisms. Interventions in humans, based on DOHaD principles, will be informed by experiments in animals. As knowledge in this discipline has accumulated, from studies of humans and other animals, the complexity of interactions between genome, environment and epigenetics, has been revealed. The vast nature of programming stimuli and breadth of effects is becoming known. As a result of our accumulating knowledge we now appreciate the impact of many variables that contribute to programmed outcomes. To guide further animal research in this field, the Australia and New Zealand DOHaD society (ANZ DOHaD) Animals Models of DOHaD Research Working Group convened at the 2nd Annual ANZ DOHaD Congress in Melbourne, Australia in April 2015. This review summarizes the contributions of animal research to the understanding of DOHaD, and makes recommendations for the design and conduct of animal experiments to maximize relevance, reproducibility and translation of knowledge into improving health and well-being.
Endothelium regulates vascular tone by influencing the contractile activity of vascular smooth muscle. This regulatory effect of the endothelium on blood vessels has been shown to be impaired in atherosclerotic arteries in humans and animals and in animal models of hypertension.
To determine whether patients with essential hypertension have an endothelium-dependent abnormality in vascular relaxation, we studied the response of the forearm vasculature to acetylcholine (an endothelium-dependent vasodilator) and sodium nitroprusside (a direct dilator of smooth muscle) in 18 hypertensive patients (mean age [+/- SD], 50.7 +/- 10 years; 10 men and 8 women) two weeks after the withdrawal of antihypertensive medications and in 18 normal controls (mean age, 49.9 +/- 9; 9 men and 9 women). The drugs were infused at increasing concentrations into the brachial artery, and the response in forearm blood flow was measured by strain-gauge plethysmography.
The basal forearm blood flow was similar in the patients and controls (mean +/- SD, 3.4 +/- 1.3 and 3.7 +/- 0.8 ml per minute per 100 ml of forearm tissue, respectively; P not significant). The responses of blood flow and vascular resistance to acetylcholine were significantly reduced in the hypertensive patients (P less than 0.0001); maximal forearm flow was 9.1 +/- 5 ml per minute per 100 ml in the patients and 20.0 +/- 8 ml per minute per 100 ml in the controls (P less than 0.0002). However, there were no significant differences between groups in the responses of blood flow and vascular resistance to sodium nitroprusside. Because the vasodilator effect of acetylcholine might also be due to presynaptic inhibition of the release of norepinephrine by adrenergic nerve terminals, the effect of acetylcholine was assessed during phentolamine-induced alpha-adrenergic blockade. Under these conditions, it was also evident that the responses to acetylcholine were significantly blunted in the hypertensive patients (P less than 0.03).
Endothelium-mediated vasodilation is impaired in patients with essential hypertension. This defect may play an important part in the functional abnormalities of resistance vessels that are observed in hypertensive patients.
The fetal origins hypothesis states that fetal undernutrition in middle to late gestation, which leads to disproportionate fetal growth, programmes later coronary heart disease. Animal studies have shown that undernutrition before birth programmes persisting changes in a range of metabolic, physiological, and structural parameters. Studies in humans have shown that men and women whose birth weights were at the lower end of the normal range, who were thin or short at birth, or who were small. in relation to placental size have increased rates of coronary heart disease. We are beginning to understand something of the mechanisms underlying these associations. The programming of blood pressure, insulin responses to glucose, cholesterol metabolism, blood coagulation, and hormonal settings are all areas of active research.
Food restriction during pregnancy in rats induces intrauterine growth retardation with consequences persisting into adulthood. In the present study we have investigated the hypothesis that malnutrition in pregnant rats may lead to altered cardiovascular function in adult female offspring. Perinatal growth retardation was induced by a 50% reduction of normal dietary intake in rats during the second half of pregnancy. Systolic and diastolic blood pressure values and heart rate were recorded in conscious female offspring (100 d old) using a femoral artery probe. No significant differences in heart rate, or in systolic and diastolic blood pressures were recorded between control offspring and offspring of nutritionally deprived rats. In order to ascertain whether cardiovascular variables in the offspring were influenced by lactation, subgroups of offspring from food-restricted dams were fostered with lactating dams fed on a normal diet. Blood pressure and heart rate were also found to be normal in these offspring. The rise in blood pressure associated with NO inhibition was similar in all groups. Isolated resistance artery function was assessed in vitro in offspring (100-120 d old) of a second group of semi-starved dams. Small mesenteric arteries from these animals showed reduced endothelium-dependent relaxation (to acetylcholine and bradykinin), but enhanced sensitivity to exogenous NO (sodium nitroprusside). We conclude that food restriction during the second half of pregnancy and/or lactation does not induce hypertension in adult offspring, but may effect subtle changes in vascular function.
Vascular aging is mainly characterized by endothelial dysfunction. We found decreased free nitric oxide (NO) levels in aged rat aortas, in conjunction with a sevenfold higher expression and activity of endothelial NO synthase (eNOS). This is shown to be a consequence of age-associated enhanced superoxide (.O(2)(-)) production with concomitant quenching of NO by the formation of peroxynitrite leading to nitrotyrosilation of mitochondrial manganese superoxide dismutase (MnSOD), a molecular footprint of increased peroxynitrite levels, which also increased with age. Thus, vascular aging appears to be initiated by augmented.O(2)(-) release, trapping of vasorelaxant NO, and subsequent peroxynitrite formation, followed by the nitration and inhibition of MnSOD. Increased eNOS expression and activity is a compensatory, but eventually futile, mechanism to counter regulate the loss of NO. The ultrastructural distribution of 3-nitrotyrosyl suggests that mitochondrial dysfunction plays a major role in the vascular aging process.
Arterial stiffness is an important determinant of cardiovascular risk. Several lines of evidence support a role for the endothelium in regulating arterial stiffness by release of vasoactive mediators. We hypothesized that nitric oxide (NO) acting locally regulates arterial stiffness in vivo, and the aim of this experiment was to test this hypothesis in an ovine hind-limb preparation.
All studies were conducted in anesthetized sheep. Pulse wave velocity (PWV) was calculated by the foot-to-foot methodology from 2 pressure waveforms recorded simultaneously with a high-fidelity dual pressure-sensing catheter placed in the common iliac artery. Intra-arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA) increased iliac PWV significantly, by 3+/-2% (P<0.01). Infusion of acetylcholine and glyceryl trinitrate reduced PWV significantly, by 6+/-4% (P=0.03) and 5+/-2% (P<0.01), respectively. Only the effect of acetylcholine, however, was significantly inhibited during coinfusion of L-NMMA (P=0.03). There was no change in systemic arterial pressure throughout the studies. Importantly, infusion of L-NMMA or acetylcholine distal to the common iliac artery (via the sheath) did not affect PWV.
These results demonstrate, for the first time, that basal NO production influences large-artery distensibility. In addition, exogenous acetylcholine and glyceryl trinitrate both increase arterial distensibility, the former mainly through NO production. This may help explain why conditions that exhibit endothelial dysfunction are also associated with increased arterial stiffness. Therefore, reversal of endothelial dysfunction or drugs that are large-artery vasorelaxants may be effective in reducing large-artery stiffness in humans, and thus cardiovascular risk.
In response to reduced oxygen or nutrient supply, the fetus may redistribute cardiac output to conserve brain and heart growth, at the expense of the peripheral tissues; however, it is not known whether alterations in vascular function are maintained after birth or whether reduced fetal oxygen versus nutrient supply produces distinct effects. Using a pressure myograph, we examined isolated carotid and femoral artery responses to phenylephrine and endothelin-1 in neonatal rats, after either reduced maternal oxygen or global nutrient restriction during late gestation. Timed-pregnant Sprague-Dawley rats were randomly assigned to control (n = 10), hypoxia (12% O2, n = 9), or nutrient restriction (NR, 40% of control diet, n = 7) protocol and treated from day 15-21 of pregnancy. Pups were collected 3-12 h after birth. Neonatal weights (P < 0.001) and relative liver weights (P < 0.001) were lower in hypoxia and nutrient restriction treatments compared with control, while relative heart weights were greater in the hypoxia than in the control or nutrient restriction groups (P < 0.01). Constriction to phenylephrine was reduced in carotid arteries from the hypoxia and nutrient restriction groups compared with control (P < 0.001), while the femoral artery response was greater in hypoxia-treated neonates compared with control or nutrient-restricted neonates (P < 0.01). Only the hypoxia reduced carotid responses to endothelin-1, while no differences were observed in the endothelin-1 responses in femoral arteries. Maternal hypoxia and maternal nutrient restriction produced distinct effects on heart growth and neonatal vascular function, suggesting that regional changes in cardiovascular function after poor fetal growth are dependent on the nature of the insult in utero.
Maternal undernutrition during critical periods of organ development is known to impair fetal growth and predispose to the development of adulthood diseases, such as hypertension, coronary heart disease and type II diabetes that are linked to low birth weight and are characterized by endothelial dysfunction. Increased oxidative stress, in rats submitted to intrauterine undernutrition, provides a potential explanation for the endothelial dysfunction development. The aim of this study was to determine the oxidative stress and its consequence on mesenteric arteriolar responses to vasoactive agents in offspring from diet-restricted dams. For this, female pregnant Wistar rats were fed either normal or 50% of normal intake diets, during the whole gestational period. In male offspring, arterial blood pressure was determined by the tail cuff method in anesthetized rats, mesenteric arteriolar reactivity and superoxide anion generation were studied using intravital microscopy and superoxide dismutase activity was determined in mesentery by spectrophotometric assay. Intrauterine undernutrition induced hypertension, decreased vasodilation to acetylcholine and bradykinin but did not alter the responses to sodium nitroprusside. Topical application of superoxide dismutase and superoxide dismutase mimetic manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin significantly improved the altered arteriolar responses to acetylcholine and bradykinin. A decreased superoxide dismutase activity and an increased superoxide anion concentration were observed in the offspring of diet-restricted dams. This study shows for the first time that intrauterine undernutrition enhances oxidative stress in vivo and relates this to the impaired endothelium-dependent vasodilation.
Objective: Epidemiological studies suggest that intrauterine undernutrition plays an important role in the development of arterial hypertension in adulthood. In an attempt to define the mechanisms whereby blood pressure may be raised, we have hypothesized that arteries from offspring of nutritionally restricted dams exhibit abnormalities in the endothelial function and in nitric oxide synthesis. In order to investigate the existence of potential gender differences on the effects of intrauterine undernutrition, both male and female offspring of pregnant Wistar rats on normal and restricted diets were studied in adulthood. Methods: Female pregnant Wistar rats were fed either normal or 50% of the normal intake diets, during the whole gestational period. At 14 weeks of age, the rats were used for the study of vascular reactivity, eNOS and iNOS gene expression, eNOS activity and, in the case of females, estrogen levels. Results: Intrauterine undernutrition induced hypertension in both male and female offspring, but hypertension was more severe in male rats. Endothelium-intact aortic rings from male and female rats in the restricted diet group exhibited increased responses to norepinephrine, decreased vasodilation to acetylcholine and unaltered responses to sodium nitroprusside in comparison to aortic rings from control rats. No gender-related differences were observed in the vascular reactivity studies. Intrauterine undernutrition promoted decreased gene expression for eNOS in aorta isolated from male, but not female, offspring, reduction in eNOS activity in both male and female offspring and impairment in synthesis of estrogen in female offspring. Conclusion: Our data show that intrauterine undernutrition: (1) induces hypertension both in the male and female offspring, hypertension being more severe in male than in female rats; (2) alters endothelium-dependent responses in aortas from the resulting offspring. The endothelial dysfunction is associated with a decrease in activity/expression of eNOS in aortas from male offspring. The mechanism involved in altered response to ACh in female offspring might be a consequence of reduction in estrogen levels leading to reduced eNOS activity.
Background— Arterial stiffness is an important determinant of cardiovascular risk. Several lines of evidence support a role for the endothelium in regulating arterial stiffness by release of vasoactive mediators. We hypothesized that nitric oxide (NO) acting locally regulates arterial stiffness in vivo, and the aim of this experiment was to test this hypothesis in an ovine hind-limb preparation.
Methods and Results— All studies were conducted in anesthetized sheep. Pulse wave velocity (PWV) was calculated by the foot-to-foot methodology from 2 pressure waveforms recorded simultaneously with a high-fidelity dual pressure-sensing catheter placed in the common iliac artery. Intra-arterial infusion of NG-monomethyl-L-arginine (L-NMMA) increased iliac PWV significantly, by 3±2% (P<0.01). Infusion of acetylcholine and glyceryl trinitrate reduced PWV significantly, by 6±4% (P=0.03) and 5±2% (P<0.01), respectively. Only the effect of acetylcholine, however, was significantly inhibited during coinfusion of L-NMMA (P=0.03). There was no change in systemic arterial pressure throughout the studies. Importantly, infusion of L-NMMA or acetylcholine distal to the common iliac artery (via the sheath) did not affect PWV.
Conclusions— These results demonstrate, for the first time, that basal NO production influences large-artery distensibility. In addition, exogenous acetylcholine and glyceryl trinitrate both increase arterial distensibility, the former mainly through NO production. This may help explain why conditions that exhibit endothelial dysfunction are also associated with increased arterial stiffness. Therefore, reversal of endothelial dysfunction or drugs that are large-artery vasorelaxants may be effective in reducing large-artery stiffness in humans, and thus cardiovascular risk.
The effects of oxidative stress on vascular function in the insulin‐resistant state were assessed in mesenteric resistance arteries of obese, insulin‐resistant (cp/cp) and lean, normal (+/?) JCR : LA‐cp rats.
Nitric oxide‐mediated relaxation of noradrenaline‐contracted arteries in response to acetylcholine was impaired after 2 h of incubation with Cu ²⁺ in both genotypes, with or without the continuing presence of Cu ²⁺ . Relaxation was enhanced on initial exposure to Cu ²⁺ , and post‐incubation removal of the Cu ²⁺ resulted in a greater impairment of relaxation. Arteries from cp/cp rats were less impaired in function by Cu ²⁺ incubation than were those of +/? controls.
Sodium nitroprusside‐mediated relaxation was impaired by exposure to Cu ²⁺ , with an accompanying increase in EC 50 .
The impairment in acetylcholine‐mediated relaxation in the arteries from both cp/cp and +/? rats was completely inhibited by co‐incubation with copper‐zinc superoxide dismutase and catalase, confirming that the impairment associated with Cu ²⁺ incubation was due to oxidative stress.
The impairment appears to involve both smooth muscle and the endothelium.
The cp/cp rats showed greater resistance to the effects of oxidative stress on arterial function, possibly due to an adaptation to oxidative stress on arterial function associated with the insulin‐resistant state.
British Journal of Pharmacology (2001) 133 , 477–484; doi: 10.1038/sj.bjp.0704095
Growth and CHDGrowth and hypertension and type 2 diabetesBiologic mechanismsResponses to adult living standardsStrength of effectsMothers and babies todayCHD epidemicsConclusion
Objective:
These studies tested whether fetal artery reactivity is sensitive to both acute changes in oxygen levels (in vitro) and chronic changes (in utero).
Study design:
Pregnant guinea pigs near term were exposed to either normoxia or hypoxia (12% oxygen) for 4 or 7 days. The effect of decreasing PO (2 ) in vitro (acute hypoxia) on relaxation in response to acetylcholine, A23187, sodium nitroprusside, and 8-bromo-cyclic guanosine monophosphate was measured in isolated carotid arteries from normoxic fetuses. In separate experiments relaxation in response to acetylcholine and sodium nitroprusside of endothelially intact and denuded fetal arteries from fetuses exposed to normoxic conditions and long-term (4 and 7 days) hypoxic conditions was measured in the presence and absence of nitro-L -arginine (10(-4) mol/L).
Results:
Acute hypoxia inhibited endothelium-dependent relaxation in response to acetylcholine and A23187, increased sensitivity to sodium nitroprusside, but had no effect on relaxation in response to 8-bromo-cyclic guanosine monophosphate. Chronic hypoxia (4 but not 7 days) inhibited maximal relaxation of arteries in response to acetylcholine but not relaxation of arteries in response to sodium nitroprusside with respect to relaxation seen in arteries from normoxic fetuses. Nitro-L -arginine attenuated the differences between normoxic and hypoxic fetuses in acetylcholine response.
Conclusion:
Hypoxia may alter relaxation of fetal arteries by decreasing the availability of oxygen for nitric oxide production and causing vascular adaptations related to altered nitric oxide release.
Pregnant rats were kept at a simulated altitude of 4,500 m (PO2 91 Torr) for the whole of gestation and returned to sea level 1 day after giving birth. During pregnancy, body weight gain and food intake were approximately 30% less than in controls at sea level. Measurements were made on the 1-day-old (HYPO) pups after a few hours at sea level. In normoxia, ventilation (VE) measured by flow plethysmography was more (+17%) and O2 consumption (VO2) measured by a manometric method was less (-19%) than in control (CONT) pups; in HYPO pups VE/VO2 was 44% greater than in CONT pups. In acute hyperoxia, VE/VO2 of HYPO and CONT pups decreased by a similar amount (15-20%), indicating some limitation in O2 availability for both groups of pups in normoxia. However, VE/VO2 of HYPO pups, even in hyperoxia, remained above (+34%) that of CONT pups. HYPO pups weighed slightly less than CONT pups, their lungs were hypoplastic, and their hearts were a larger fraction of body weight. An additional group of female rats was acclimatized (8 days) to high altitude before insemination. During pregnancy, body weight gain and food intake of these females were similar to those of pregnant rats at sea level. Measurements on the 1-day-old pups of this group were similar to those of HYPO pups. We conclude that newborn rats born after hypoxic gestation present metabolic adaptation (low VO2) and acclimatization (high VE/VO2), possibly because of hypoxemia. Maternal acclimatization before insemination substantially alters maternal growth in hypoxia but does not affect neonatal outcome.
In isolated blood vessels, acetylcholine releases endothelium-derived relaxing factor (EDRF). In vivo, the vasodilator action of acetylcholine may be mediated by EDRF, but prostacyclin or prejunctional inhibition of adrenergic neurotransmission may also be involved. Therefore, we investigated whether acetylcholine releases EDRF in humans in vivo and, if so, whether the response altered in essential hypertension. Acetylcholine was infused into the brachial artery, and forearm blood flow measured by venous occlusion plethysmography. In control subjects, acetylcholine (0.02-16 micrograms/min/100 ml tissue) increased flow from 2.4 +/- 5.0 to 20.6 +/- 5.2 ml/min/100 ml tissue (n = 14; p less than 0.05) and decreased forearm vascular resistance from 42.0 +/- 4.1 to 6.0 +/- 1.4 units (p less than 0.03), a response comparable to that of sodium nitroprusside (0.6 micrograms/min ml tissue). Acetylsalicylic acid (500 mg i.v.) given to block vascular prostacyclin production did not alter the response (n = 14). alpha-Adrenoceptor blockade by phentolamine (12 micrograms/min/100 ml tissue) did not prevent the increase in flow evoked by acetylcholine. In hypertensive patients, the decrease in forearm vascular resistance induced by acetylcholine but not evoked by sodium nitroprusside was reduced as compared with controls (14.5 +/- 3.1 and 6.1 +/- 1.6 units, respectively; n = 8; p less than 0.05). Thus, the vascular effects of acetylcholine in the human forearm circulation are independent of prostaglandins and adrenergic neurotransmission and therefore are most likely to be mediated by EDRF; the acetylcholine-induced release of EDRF is blunted in patients with essential hypertension.
NG monomethyl-L-arginine (L-NMMA), a specific inhibitor of the synthesis of endothelium-derived nitric oxide (NO), was infused into the brachial arteries of healthy volunteers to study the role of NO in the control of forearm blood flow. L-NMMA caused a 50% fall in basal blood flow and attenuated the dilator response to infused acetylcholine but not that to glyceryl trinitrate. These results indicate that the dilator action of endothelium-derived NO contributes to the control of basal and stimulated regional blood flow in man. Impairment of production of NO might account for the abnormalities in vascular reactivity that characterise a wide variety of disease states.
Experiments were designed to determine the effects of oxygen-derived free radicals on the production and biological activity of endothelium-derived relaxing factor or factors released by acetylcholine. Rings of canine coronary arteries without endothelium (bioassay rings) were superfused with solution passing through a canine femoral artery with endothelium. Superoxide dismutase caused maximal relaxation of the bioassay ring when infused upstream, but not downstream, of the femoral artery; this effect of superoxide dismutase was inhibited by catalase. Infusion of acetylcholine relaxed the bioassay rings because it released a labile relaxing factor (or factors) from the endothelium. When infused below the femoral artery, superoxide dismutase and, to a lesser extent, catalase augmented the relaxations to acetylcholine. Superoxide dismutase, but not catalase, doubled the half-life of the endothelium-derived relaxing factor(s). This protective effect of the enzyme was augmented fivefold by lowering the oxygen content of the perfusate from 95 to 10%. These data demonstrate that: superoxide anions inactivate the relaxing factor(s) released by acetylcholine from endothelial cells and hyperoxia favors the inactivation of endothelium-derived relaxing factor(s).
Three groups of pregnant Wistar rats were subjected to 3 different levels of hypoxia: 11.6, 10.7 and 9.0%, respectively. Pair-fed and ad libitum fed control groups were included to control for the reduced food intake due to hypoxia. Within the range studied, fetal body weights decreased with decreased oxygen availability. Liver weights were more, brain weights less markedly reduced than body weights. Pair-fed but normally oxygenated animals showed slight reductions in body and organ weights compared to ad libitum fed controls. The fetuses subjected to hypoxia showed a placental hypertrophy relative to their body weights, while the least hypoxic fetuses showed an absolute placental hypertrophy. Placenta-fetal body ratios that were 150% greater than those observed in control animals were documented. In contrast, the fetuses of food-deprived animals were associated with abnormally small placentas.
A noninvasive technique in an animal model that consistently produces severe intrauterine growth retardation in the Sprague-Dawley rat is described. Maternal rats were exposed continuously to a hypoxic environment (9.5% oxygen) between days 10 and 22 of gestation. This oxygen concentration was marginal for the survival of the Sprague-Dawley rat fetus. The results demonstrate decreases of 61% in litter size, 36% in fetal body weight, and 23% in fetal brain weight. The effect of hypoxia was differentiated from that of a reduced voluntary food intake by the maternal rats occurring simultaneously during the period of hypoxic exposure.
The effects of NG-monomethyl-L-arginine (L-NMMA) on total finger and forearm, and dorsal finger and forearm skin, blood flows were studied in the basal state and during reflex sympathetic vasoconstriction in normal subjects. Total flows were measured by venous occlusion plethysmography and skin flows by laser-Doppler flowmetry (LDF). L-NMMA in doses of 2, 4, and 8 microM/min given by constant infusion via a brachial artery catheter significantly decreased finger blood flow, forearm blood flow, and vascular conductances. At 8 microM/min, total finger blood flow decreased 38.4% and forearm blood flow decreased 24.8%. Dorsal finger and forearm skin LDF were also significantly decreased (25 and 37% at 8 microM/min). Body cooling significantly decreased finger blood flow (73.6%), vascular conductance, and finger LDF (59.7%). L-NMMA had no effect on total finger blood flow or dorsal finger LDF during body cooling. Nitric oxide or related compounds contribute to the basal dilator tone of the dorsal finger and forearm skin but not during reflex sympathetic vasoconstriction.
Recent studies indicate that nitric oxide (NO) and guanosine 3',5'-cyclic monophosphate (cGMP) may inhibit the proliferation of vascular smooth muscle cells (SMC) in vitro. The purpose of this study was to investigate the mechanism of NO- and cGMP-dependent inhibition of cultured rat aortic SMC. The cytokine interleukin-1 beta (IL-1 beta) inhibited serum- and platelet-derived growth factor-stimulated [3H]thymidine incorporation into DNA in subcultured rat aortic SMC. Incubation with IL-1 beta for 24 h markedly increased cGMP levels but not adenosine 3',5'-cyclic monophosphate (cAMP) levels. However, the IL-1 beta-induced increase in cGMP was correlated with an activation of the cAMP-dependent protein kinase (cAMP kinase) activity ratio. The activation of the cAMP kinase was prevented by treatments that blocked NO and cGMP production. The NO-generating vasodilator, S-nitroso-N-acetylpenicillamine (SNAP) also inhibited DNA synthesis and elevated cGMP levels. The inhibition of DNA synthesis by both IL-1 beta and SNAP was observed only when cGMP levels were elevated to high levels (10-fold or more). As was the case for IL-1 beta, SNAP increased the activity ratio of cAMP kinase. Selective inhibition of cAMP kinase using (R)-p-bromoadenosine 3',5'-cyclic monophosphorothioate prevented the inhibition of proliferation by IL-1 beta. By contrast, the inhibitor of the cGMP-dependent protein kinase, (R)-p-bromoguanosine 3',5'-cyclic monophosphorothioate, had no effect on IL-1 beta-induced inhibition of cellular proliferation. These studies suggest that cGMP-dependent activation of the cAMP kinase may be responsible in part at least for the NO-dependent inhibition of proliferation of subcultured rat aortic SMC.
The fetal origins hypothesis states that fetal undernutrition in middle to late gestation, which leads to disproportionate fetal growth, programmes later coronary heart disease. Animal studies have shown that undernutrition before birth programmes persisting changes in a range of metabolic, physiological, and structural parameters. Studies in humans have shown that men and women whose birth weights were at the lower end of the normal range, who were thin or short at birth, or who were small in relation to placental size have increased rates of coronary heart disease. We are beginning to understand something of the mechanisms underlying these associations. The programming of blood pressure, insulin responses to glucose, cholesterol metabolism, blood coagulation, and hormonal settings are all areas of active research.
We tested the hypothesis that oxidative stress, mediated by dietary vitamin E deprivation, would alter vascular function through the interaction of oxygen-derived free radicals and nitric oxide (NO). This interaction may play an important role in the vascular pathophysiology of many diseases associated with oxidative stress. Mesenteric arteries from control (n = 12) and vitamin E-deprived (n = 12) Sprague-Dawley rats were studied with a myograph. Superoxide dismutase, which scavenges superoxide anions, produced a significantly greater relaxation in the arteries from the vitamin E-deprived rats compared with the controls (P<.05). Superoxide dismutase and catalase produced results similar to superoxide dismutase alone. Pretreatment with an NO synthase inhibitor eliminated the superoxide dismutase-induced relaxation in arteries from both control and vitamin E-deprived rats. L-Arginine induced a greater relaxation in arteries of the vitamin E-deprived group (P<.05). Agonist-induced relaxation with methacholine was not altered by superoxide dismutase for either group of animals, indicating that stimulated release of NO was not influenced by superoxide anions. With the use of Western immunoblot analysis, nitrotyrosine residues were shown to be present in arteries from both the vitamin E-deprived and control rats, but the amount of nitrotyrosine observed was not different between the two groups. In summary, our data indicate that there is a greater inhibition of NO caused by superoxide anions in the vitamin E-deprived group. We speculate that in conditions of oxidative stress (reduced vitamin E levels), altered vascular function may be due to increased destruction of NO by oxygen-derived free radicals.
Two NO synthase (NOS) isoforms have been described in vessels, an endothelial constitutive NOS (eNOS) and an inducible NOS (iNOS). The purpose of the present study was to examine the endothelium-dependent and endothelium-independent hypotensive response in aging rats, analyzing the ability of their vessels to produce NO. The studies were performed in 2 groups of euvolemic, conscious, male Wistar rats: aging rats (n=20, 18 months old) and young rats (n=20, 5 months old). The hypotensive responses to acetylcholine, bradykinin, and sodium nitroprusside were determined. Furthermore, the expression of the NOS isoforms by Western blot and the eNOS and iNOS activities, defined as Ca2+-dependent and Ca2+-independent conversion of [14C]L-arginine into [14C]L-citrulline, respectively, were also determined. In the aging rats, we found an impaired hypotensive response to acetylcholine and bradykinin (2 NO- and endothelium-dependent hypotensive agents) that was accompanied by a preserved hypotensive response to sodium nitroprusside. Aging rats also demonstrated an enhanced sensitivity response to the pressor effect of the L-arginine antagonist L-Nomega-nitro-L-arginine and a reduced vasoconstrictor response to angiotensin II. The inhibition of NO synthesis normalized the pressor effect of angiotensin II in the aging animals. Nitrite plus nitrate plasma levels were increased in aging rats. Furthermore, cGMP content was also higher in the aging vessels. In the aging aortas, the expression of both eNOS and iNOS isoforms was enhanced. However, in aging rats, the activity of the eNOS isoform was markedly reduced, a finding that was accompanied by the presence of iNOS activity. The vessel wall of aging rats showed an enhanced expression of eNOS and iNOS isoforms. However, eNOS activity was reduced in the aging animals. These findings could explain the impaired endothelium-dependent hypotensive response associated with aging.
Non-insulin-dependent diabetes, hypertension and ischaemic heart disease, with insulin resistance, are associated with low birth weight (the 'Small Baby Syndrome'). Common to these adult clinical conditions is endothelial dysfunction. We tested the hypothesis that endothelial dysfunction could precede their development in those of low birth weight.
Endothelial function was measured by ultrasonic 'wall-tracking' of flow-related brachial artery dilatation in fit 19-20 year old subjects randomly selected (blind to the investigators throughout the study) from low (< 2.5 kg) and normal (3.0-3.8 kg) birth weight subjects in the 1975-7 cohort of the Cardiff Births Survey and with no known cause for endothelial dysfunction.
Flow-related dilatation was impaired in low birth weight relative to normal birth weight subjects (median 0.04 mm [1.5%] [n = 22] cf. 0.11 mm [4.1%] [n = 17], p < 0.05; 0.04 mm [1.5%] [n = 15] cf. 0.12 mm [4.4%] [n = 12], p < 0.05 after exclusion of inadvertently included ever-smokers).
The findings suggest that endothelial dysfunction is a consequence of foetal malnutrition, consistent with contributing to the clinical features of the 'Small Baby Syndrome' in later adult life.
cAMP and cGMP are known to suppress vascular smooth muscle cell (SMC) proliferation. In this study, our aim was to delineate the molecular mechanism underlying cAMP and cGMP suppression of cell cycle transition in human SMCs. cAMP inhibits both platelet-derived growth factor-stimulated cyclin-dependent kinase (cdk) 2 and cdk4 activation through upregulation of the cdk2 inhibitor p27(Kip1) and downregulation of cyclin D1 expression, which leads to a complete arrest of the cells in phase G(1). In contrast, cGMP inhibits cyclin D1 expression, inhibits cdk4 activation, and delays platelet-derived growth factor-mediated cdk2 activation, resulting in a delay in G(1)/S transition. A transient increase in p27(Kip1) in cdk2 immunoprecipitates, without changes in total cellular p27(Kip1) levels, correlates with the delay in cdk2 activation caused by cGMP. Thus, cAMP and cGMP differentially affect cell cycle through distinct regulation of cell cycle molecules in human SMCs.
Low birth weight is associated with an increased risk of adult hypertension. To elucidate whether this association reflects altered vascular physiology already at birth, we studied acetylcholine-induced vasodilation. Forty newborn infants and their mothers were studied 3 d after delivery. Vasodilation in skin was induced by local application of acetylcholine and local heating to 44 degrees C. Perfusion changes were measured with the laser Doppler technique. In response to acetylcholine, the mean skin perfusion increased by 240% in low birth weight infants compared with 650% in normal birth weight controls (p < 0.001). In contrast, mothers of low birth weight infants showed a mean increase in perfusion of 1100% after acetylcholine administration compared with 680% in mothers of control infants (p < 0.05). The perfusion increase at 44 degrees C local skin temperature did not differ between the two groups of infants or between their mothers. Blood pressure was normal in all subjects. We conclude that low birth weight infants show signs of endothelial dysfunction at birth. Such findings may help us understand the link between low birth weight and adult hypertension.
During aging, the vascular endothelium changes functionally and morphologically. Although previous studies have shown that endothelium-derived eicosanoids increase vessel tone in aging, the precise mechanism(s) has not been fully determined. We hypothesized that aging would increase prostaglandin H synthase (PGHS)-dependent vasoconstriction as well as decrease nitric oxide-dependent relaxation. Mesenteric arteries from 3-month-old (n=9) and 12-month-old (n=14) female Sprague-Dawley rats were studied in a myograph system. Aging significantly blunted the endothelium-dependent relaxation response to methacholine compared with young rats (EC(50)=7.77x10(-8) versus 2.68x10(-8) mol/L, P<0. 05). Nitric oxide synthase inhibition reduced methacholine-induced relaxation in the young (P<0.05) but had no effect in the aging group. Specific inhibition of the PGHS-1 isoform did not significantly affect methacholine-mediated relaxation in the young or aged groups. However, PGHS-2 inhibition greatly enhanced relaxation to methacholine (1.59x10(-8) versus 7.77x10(-8) mol/L, P<0.01) in the aged group only, restoring vessel function to that of the young. In the aged group, inhibition of the prostaglandin H(2)/thromboxane A(2) receptor enhanced methacholine-dependent relaxation similar to that of PGHS-2 inhibition. Moreover, arterial expression of PGHS-2 protein increased with age. In summary, nitric oxide-dependent modulation of vessel function decreased with age, PGHS-1 did not significantly affect vessel tone in either the young or aging group, and PGHS-2 greatly increased vasoconstriction in aging. Thus, we have identified enhanced PGHS-2-mediated vasoconstriction in aging and therefore suggest that inhibition of this isoform is potentially a new target for therapeutic intervention to improve vascular function.
To conduct a systematic review in order to (i) summarize the relationship between birthweight and blood pressure, following numerous publications in the last 3 years, (ii) assess whether other measures of size at birth are related to blood pressure, and (iii) study the role of postnatal catch-up growth in predicting blood pressure.
All papers published between March 1996 and March 2000 that examined the relationship between birth weight and systolic blood pressure were identified and combined with the papers examined in a previous review.
More than 444,000 male and female subjects aged 0-84 years of all ages and races.
Eighty studies described the relationship of blood pressure with birth weight The majority of the studies in children, adolescents and adults reported that blood pressure fell with increasing birth weight, the size of the effect being approximately 2 mmHg/kg. Head circumference was the only other birth measurement to be most consistently associated with blood pressure, the magnitude of the association being a decrease in blood pressure by approximately 0.5 mmHg/cm. Skeletal and non-skeletal postnatal catch-up growth were positively associated with blood pressure, with the highest blood pressures occurring in individuals of low birth weight but high rates of growth subsequently.
Both birth weight and head circumference at birth are inversely related to systolic blood pressure. The relationship is present in adolescence but attenuated compared to both the pre- and post-adolescence periods. Accelerated postnatal growth is also associated with raised blood pressure.
Endothelial dysfunction has been described with ageing but the mechanisms responsible have not been clearly elucidated and might be different from one vessel to the other. This study assesses the relative contribution of endothelial nitric oxide (NO) and cyclo-oxygenase (COX) metabolites in relaxation to acetylcholine with ageing in the aorta and the small mesenteric artery of the rat.
In the aorta and branch II or III of superior mesenteric artery (SMA), endothelium-dependent relaxation to acetylcholine was not different between 12–14 (adult) and 32-week-old rats whereas it was reduced at 70–100 (old) weeks of age.
Despite an increased endothelial NO-synthase protein expression, the NO-synthase inhibitor, NG-nitro-L-arginine-sensitive component of relaxation decreased with ageing.
In old rats, exposure to the COX inhibitor, indomethacin, but not the selective COX-2 inhibitor, NS-398, potentiated response to acetylcholine. The thromboxane A2/prostaglandin H2 receptor antagonist, GR 32191B enhanced relaxation to acetylcholine in aorta but it had no effect in SMA. Furthermore, acetylcholine increased thromboxane B2 production (enzymeimmunoassay) in aorta but not in SMA. Finally, Western blot analysis showed enhanced expression of COX-1 and 2 in the two arteries with ageing.
These results suggest that the decrease in acetylcholine-induced relaxation with ageing involves reduced NO-mediated dilatation and increased generation of vasoconstrictor prostanoids most likely from COX-1. They also point out vascular bed heterogeneity related to the nature of prostanoids involved between the aorta (i.e., thromboxane A2) and the SMA (unidentified) arteries even though increased expression of COX occurs in both vessels.
British Journal of Pharmacology (2000) 131, 303–311; doi:10.1038/sj.bjp.0703568
The aim of this study was to investigate functional development of small arteries from the skeletal circulation of fetal sheep and to determine whether maternal undernutrition affects responses to vasoconstrictive and vasodilatory agonists in arteries from the late-gestation fetus.
We investigated vasoconstrictive and vasodilatory responses of isolated small (approximately 300 microm) arteries from the femoral vascular bed of fetal sheep and from late-gestation pregnant ewes. Ewes were fed either 100% of the nutritional requirement throughout pregnancy (control group) or a restricted diet of 85% or 50% of the nutritional requirement for the first 70 days of pregnancy. For the remainder of pregnancy all ewes were fed the complete diet.
Among control group animals vasoconstriction in response to norepinephrine was well developed in fetuses at 0.6 and 0.9 gestation with respect to that in the ewes. When expressed as a percentage of the response to 125-mmol/L potassium (to correct for differences in vessel size and muscle mass), maximum constriction in response to norepinephrine was greater in fetal vessels from 0.9 gestation than in either those at 0.6 gestation or those of the ewes. Endothelium-dependent vasorelaxation responses to acetylcholine and bradykinin were also well developed in fetuses at 0.6 and 0.9 gestation and were similar to those in the ewes. In fetuses at 0.9 gestation the 50% nutritional restriction of the ewe led to blunted endothelium-dependent vasodilatation in response to acetylcholine and blunted endothelium-independent vasodilatation in response to sodium nitroprusside. Responses in the fetuses at 0.9 gestation in which the ewes were fed a restricted diet of 85% were normal.
This study shows that from midgestation onward small arteries from the skeletal circulation of the fetal sheep have the functional capacity to respond to norepinephrine and endothelium-dependent vasodilators (eg, acetylcholine and bradykinin). The blunted responses to acetylcholine and sodium nitroprusside in the fetuses at 0.9 gestation among the group of dietarily restricted ewes (restricted diet of 50% group) were indicative of impaired vascular smooth muscle sensitivity to nitric oxide. This defect may contribute to the development of hypertension in later life.
Low birthweight (LBW) has been associated with an increased incidence of adult cardiovascular disease. Endothelial dysfunction and loss of arterial elasticity are early markers of hypertension and atherosclerosis. We studied the prevalence of these markers in 44 healthy, prepubertal (age 9+/-1.3 years) children, 22 with LBW for age.
Endothelial function in skin was tested with the local application of acetylcholine (inducing endothelium-dependent vasodilation) and nitroglycerin (endothelium-independent vasodilation), and local perfusion changes were measured with the laser Doppler method. The elastic properties of the abdominal aorta and common carotid artery were measured with an ultrasonic vessel-wall tracking system. Endothelium-dependent vasodilation was lower in children with LBW (88+/-33 perfusion units [PU]) than in normal-birthweight controls (133+/-34 PU, P<0.001). There was no difference in aortic or carotid elasticity between the 2 groups, but a negative correlation was found between birthweight and stiffness of the carotid artery wall (r=-0.45, P<0.01). Endothelium-independent vasodilation and blood pressure were similar in the 2 groups.
Schoolchildren with a history of LBW show impaired endothelial function and a trend toward increased carotid stiffness. These findings may be early expressions of vascular compromise, contributing to susceptibility to disease in adult life.
We have investigated the effects of moderate global undernutrition during gestation in the rat on the blood pressure of male and female offspring, and on the development of systemic vascular function. Pregnant Wistar rats were nutritionally restricted (R) by feeding with 70% of the normal gestation-matched dietary intake from 0 to 18 days gestation.
R offspring were growth retarded at birth but of similar weight to controls (C) at 20 days. Systolic and/or diastolic and mean arterial blood pressures, measured directly by femoral artery catheter, were elevated from 60 days onward in male R offspring (mean arterial pressure: day 60, P < 0.01; day 100, P < 0.05; day 200, P < 0.005, R vs. C), and from 100 days onward in female R offspring (mean arterial pressure day 100 and day 200, P < 0.05; R vs. C).
Maximal constriction to phenylephrine (PE) (P < 0.05) and to noradrenaline (NA) (P < 0.05) was reduced in isolated femoral arteries of day 20 R pups. These differences did not persist into adulthood. In male adult R offspring (200 days), maximal vasoconstriction to the thromboxane A2 mimetic, U46619 (P < 0.05) and sensitivity to potassium (P < 0.01) were enhanced.
Moderate maternal undernutrition in rat gestation adversely affects cardiovascular function in the offspring. These abnormalities increase with age and are more pronounced in males.
Low birth weight is related to increased risk of coronary heart disease in adults and recently has been associated with vascular endothelial dysfunction in children. We investigated whether the relation between birth weight and endothelial function was still present in early adult life and whether there was an interaction with emerging risk factors.
In 315 adults (165 women, 150 men, aged 20 to 28 years), high-resolution ultrasound was used to determine endothelium-dependent and -independent vascular responses of the brachial artery. Vascular measures were related to classic risk factors (smoking history, lipid profile, blood pressure, fasting insulin, exercise capacity, body mass index, and combined risk score) and birth weight. Low birth weight was associated with reduced flow-mediated dilation (coefficient=0.18 kg(-1), 95% CI 0.004 to 0.35, P:=0.04) but not with endothelium-independent dilation. The difference in flow-mediated dilation between the top and bottom fifths of birth weight was the same as between smokers and nonsmokers. Increasing levels of acquired risk factors overwhelmed the association, and there was a significant interaction of risk score with the birth weight-endothelial function relation (coefficient of interaction term [birth weightxrisk score] = -0.12, 95% CI -0.22 to -0.03, P:=0.01).
Low birth weight is associated with endothelial dysfunction in young adults. This is most marked in individuals with lower risk factor profiles and may be relevant to the pathogenesis of atherosclerosis in later life.
Arterial elasticity is determined by structural characteristics of the artery wall and by vascular smooth muscle tone. The identity of endogenous vasoactive substances that regulate elasticity has not been defined in humans. We hypothesized that NO, a vasodilator released constitutively by the endothelium, augments arterial elasticity. Seven healthy young men were studied. A 20-MHz intravascular ultrasound catheter was introduced through an arterial sheath to measure brachial artery cross-sectional area, wall thickness, and intra-arterial pressure. After control was established, indices of elasticity (pressure-area relationship, instantaneous compliance, and stress-strain, pressure-incremental elastic modulus (E(inc)), and pressure-pulse wave velocity relationships) were examined over 0 to 100 mm Hg transmural pressure obtained by inflation of an external cuff. Thereafter, the basal production of endothelium-derived NO was inhibited by N(G)-monomethyl-L-arginine (L-NMMA) (4 and 8 mg/min). Finally, nitroglycerin (2.5 and 12.5 microgram/min), an exogenous donor of NO, was given to relax the vascular smooth muscle. Elasticity was measured under all of these conditions. L-NMMA (8 mg/min) decreased brachial artery area (P=0.016) and compliance (P<0.0001) and increased E(inc) (P<0.01) and pulse wave velocity (P<0.0001). Nitroglycerin (12.5 microgram/min) increased brachial artery area (P<0.001) and compliance (P<0.001) and decreased pulse wave velocity (P=0.02). NO, an endothelium-derived vasodilator, augments arterial elasticity in the human brachial artery. Loss of constitutively released NO associated with cardiovascular risk factors may adversely affect arterial elasticity in humans.
The 'Fetal origins hypothesis' states that individuals born small because of malnutrition are predisposed to adult diseases. Fetal malnutrition has two main causes, poor maternal nutrition and placental insufficiency. A distinction between these causes is important because it is likely that maternal nutrition has been sufficient in the majority of populations in which the fetal origins hypothesis has been tested. Thus, placental insufficiency is a more reasonable cause of reduced fetal growth in adequately nourished populations. Placental insufficiency is mainly due to inadequate vascular adaptation at the uteroplacental interface ('poor placentation'). Among women with placental insufficiency syndromes such as pre-eclampsia and 'idiopathic' intrauterine growth retardation, there is an increased prevalence of risk factors for cardiovascular diseases. Maternal cardiovascular risk factors may therefore increase the risk of adult diseases in the offspring both through direct inheritance and by interfering with uteroplacental vascular adaptation. The latter may result in placental insufficiency and fetal growth retardation that by itself could cause adult disease (as the Fetal origins hypothesis states). Alternatively, the association between low birth weight for gestational and adult disease could be an epiphenomenon, leaving inheritance as the main explanation for the fetal origins hypothesis, in adequately nourished populations.
Epidemiological studies suggest that intrauterine undernutrition plays an important role in the development of arterial hypertension in adulthood. In an attempt to define the mechanisms whereby blood pressure may be raised, we have hypothesized that arteries from offspring of nutritionally restricted dams exhibit abnormalities in the endothelial function and in nitric oxide synthesis. In order to investigate the existence of potential gender differences on the effects of intrauterine undernutrition, both male and female offspring of pregnant Wistar rats on normal and restricted diets were studied in adulthood.
Female pregnant Wistar rats were fed either normal or 50% of the normal intake diets, during the whole gestational period. At 14 weeks of age, the rats were used for the study of vascular reactivity, eNOS and iNOS gene expression, eNOS activity and, in the case of females, estrogen levels.
Intrauterine undernutrition induced hypertension in both male and female offspring, but hypertension was more severe in male rats. Endothelium-intact aortic rings from male and female rats in the restricted diet group exhibited increased responses to norepinephrine, decreased vasodilation to acetylcholine and unaltered responses to sodium nitroprusside in comparison to aortic rings from control rats. No gender-related differences were observed in the vascular reactivity studies. Intrauterine undernutrition promoted decreased gene expression for eNOS in aorta isolated from male, but not female, offspring, reduction in eNOS activity in both male and female offspring and impairment in synthesis of estrogen in female offspring.
Our data show that intrauterine undernutrition: (1) induces hypertension both in the male and female offspring, hypertension being more severe in male than in female rats; (2) alters endothelium-dependent responses in aortas from the resulting offspring. The endothelial dysfunction is associated with a decrease in activity/expression of eNOS in aortas from male offspring. The mechanism involved in altered response to ACh in female offspring might be a consequence of reduction in estrogen levels leading to reduced eNOS activity.
Maternal undernutrition during critical periods of organ development is known to impair fetal growth and predispose to the development of adulthood diseases, such as hypertension, coronary heart disease and type II diabetes that are linked to low birth weight and are characterized by endothelial dysfunction. Increased oxidative stress, in rats submitted to intrauterine undernutrition, provides a potential explanation for the endothelial dysfunction development. The aim of this study was to determine the oxidative stress and its consequence on mesenteric arteriolar responses to vasoactive agents in offspring from diet-restricted dams. For this, female pregnant Wistar rats were fed either normal or 50% of normal intake diets, during the whole gestational period. In male offspring, arterial blood pressure was determined by the tail cuff method in anesthetized rats, mesenteric arteriolar reactivity and superoxide anion generation were studied using intravital microscopy and superoxide dismutase activity was determined in mesentery by spectrophotometric assay. Intrauterine undernutrition induced hypertension, decreased vasodilation to acetylcholine and bradykinin but did not alter the responses to sodium nitroprusside. Topical application of superoxide dismutase and superoxide dismutase mimetic manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin significantly improved the altered arteriolar responses to acetylcholine and bradykinin. A decreased superoxide dismutase activity and an increased superoxide anion concentration were observed in the offspring of diet-restricted dams. This study shows for the first time that intrauterine undernutrition enhances oxidative stress in vivo and relates this to the impaired endothelium-dependent vasodilation.
Dietary protein restriction during gestation has been shown to produce vascular dysfunction in pregnant rats and hypertension in their offspring. However, no studies have to date examined the effects of such 'programming' on the vascular function of female offspring when they in turn become pregnant. We have therefore studied isolated conduit and resistance artery function from pregnant female offspring of control (C, 18 % casein) and protein-restricted (PR, 9 % casein) pregnant dams. There were no differences in birth weight, weight gain during pregnancy, litter size, fetal weight, placental weight, fetal : placental weight ratio or organ weights between the C and PR groups. In isolated mesenteric arteries, the vasodilatation in response to the endothelial-dependent vasodilator acetylcholine (ACh) and the beta-adrenoceptor agonist isoprenaline was decreased in the PR group, while there were no differences in the constriction in response to potassium (125 mM) or the alpha1-adrenoceptor agonist phenylephrine (PE). No differences in any responses were seen in the isolated thoracic aorta. We conclude that dietary protein restriction in pregnancy programmes vasodilator dysfunction in isolated resistance arteries of female offspring when they become pregnant, but does not affect conduit arteries.
It is established that dietary protein restriction of pregnant rats results in their offspring developing hypertension. However, to date no studies have investigated peripheral vascular function of offspring using the low protein model. Therefore, the aim of the study was to assess isolated resistance artery function from adult male offspring of control (C, 18% casein) and protein-restricted (PR, 9% casein) pregnant dams at two different ages. The birthweight of PR offspring did not significantly differ from that of C offspring. Systolic blood pressure was significantly elevated in PR compared with C (p < 0.05). Maximal vascular contraction to phenylephrine and the thromboxane analog U46619 were similar in C and PR offspring at postnatal d 87 and 164. Relaxation induced by the endothelium-dependent vasodilators acetylcholine or bradykinin was significantly reduced in the PR group (p < 0.05). Relaxation to the endothelium-independent vasodilator sodium nitroprusside and phosphodiesterase type 3 inhibitor cilostamide was less in the PR offspring compared with C (p < 0.01). Dietary protein restriction in pregnancy induces hypertension and vascular dysfunction in male offspring. Abnormalities in the nitric oxide-cGMP pathway may explain the defect in endothelium-dependent and -independent relaxation. Reduced vasodilation may be a potential mechanism underlying the elevated systolic blood pressure observed in this model.
Low birth weight predisposes to later coronary disease. To further elucidate the mechanisms behind this association and their timing, vascular endothelial function-a key factor in early pathophysiology of atherosclerosis-was studied in 54 infants born either before the third trimester or at term.
All subjects were studied at 3 months of postnatal age. A laser-Doppler technique was used to measure skin perfusion before and after transdermal iontophoresis of acetylcholine (ACh; an endothelium-dependent vasodilator). In infants born at term (n=19; birth weight range: 2230 to 4205 g), maximum perfusion after ACh was 109+/-8 perfusion units (PU, mean+/-SEM) in normal-birth weight controls compared with 56+/-13 PU among those who had been small for gestational age at birth (P<0.01). In infants born preterm (n=35; birth weight range, 722 to 1868 g), ACh induced similar perfusion responses among subjects appropriate for gestational age (113+/-16 PU) and in those small for gestational age at birth (109+/-19 PU).
Impairment in human endothelial function associated with low birth weight occurs or emerges late in pregnancy. Very preterm birth attenuates this association. Different gene-environment interactions in the third trimester may contribute to this finding.
Unbalanced maternal nutrition affects fetal endocrine and cardiovascular systems, sometimes accompanied by changes in growth, although this is usually in late gestation. We determined the effect of moderate restriction for the first half of gestation of maternal dietary protein, or of total calorific intake on isolated resistance artery function of mid-gestation fetal sheep. Welsh Mountain ewes were nutritionally restricted by 30 % of the recommended nutrient intake (globally restricted) or 30 % of the recommended protein intake (protein-restricted), compared to control ewes fed 100 % of recommended nutrient intake, for ~12 days prior to conception and for the subsequent 70 days of gestation. At mid-gestation, fetal and placental weights were similar in all dietary groups. In isolated femoral arteries, the response curve to noradrenaline was reduced in protein-restricted group fetuses (P < 0.05). Maximal relaxation (P < 0.01) and sensitivity (P < 0.05) to acetylcholine were markedly reduced in protein-restricted group fetuses, and to a smaller extent in globally restricted group fetuses (response curve, P < 0.05). The dilator response (P < 0.05) and sensitivity (P < 0.05) to the alpha2 agonist UK14304 was lower in protein-, but not in globally restricted group fetuses. The response (P < 0.05) and sensitivity (P < 0.05) to the nitric oxide donor sodium nitroprusside were reduced in protein-restricted group fetuses compared to controls. Our data show that dietary imbalance, in particular restricted protein, of the ewe can produce blunting of endothelial-dependent and -independent relaxation in systemic arteries from the mid-gestation fetus. These changes may precede perturbed late-gestation fetal and postnatal cardiovascular control.
We previously observed arterial sympathetic hyperinnervation and endothelial dysfunction in the chicken embryo after exposure to chronic hypoxia. We now investigate whether changes in arterial properties could also be observed at 14-15 weeks of life. Eggs of White Leghorn chicken were incubated under normoxic or moderately hypoxic (15% O2 from days 6-19 of a 21-day incubation) conditions. Experiments were performed at 14-15 weeks of life under standard conditions (Hm: males exposed to hypoxia; Hf: females exposed to hypoxia; Nm: males exposed to normoxia; Nf: females exposed to normoxia). Body weight at hatching and at 14-15 weeks was not affected by in ovo exposure to hypoxia. Mean arterial pressure and heart rate were not significantly altered by chronic in ovo hypoxia. However, isolated femoral arteries were more sensitive to electrical stimulation (frequency in Hz of half-maximal contraction, Hm: 1.62+/-0.33, Hf: 1.92+/-0.88, Nm: 2.49+/-0.49, Nf: 2.83+/-0.31) and pharmacological stimulation of peri-arterial sympathetic nerves (contraction in N/m in response to tyramine: Hm: 5.27+/-0.85, Hf: 4.10+/-0.9, Nm: 2.26+/-0.67, Nf: 3.65+/-0.51, p=0.07) after in ovo hypoxia. In side branches of the femoral artery, the effect of NO synthase blockade with L-NAME on contraction (in N/m) in response to high K+ (Hm: 0.35+/-0.91, Hf: 1.29+/-0.36, Nm: 2.88+/-0.19, Nf: 2.79+/-0.58) and on the sensitivity to acetylcholine (DeltapD2, H: 0.32+/-0.11, N: 0.62+/-0.05) was reduced after in ovo hypoxia. The present study shows that exposure to chronic moderate hypoxia during development affects the contractile and relaxing arterial responses of 14- to 15-week-old chickens. Although hypoxia did not lead to changes in blood pressure at this age, the observed effects on arterial sympathetic and endothelial function may represent early signs of future cardiovascular abnormalities.
In the present study, we investigated the effects of the exogenous application of tetrahydrobiopterin on the endothelium-dependent vasorelaxation and superoxide anion generation in the mesenteric microvessels of intrauterine undernourished rats. In addition, we investigated the presence of peroxynitrite in these rats by evaluation of nitrotyrosine-containing proteins, a stable end-product of peroxynitrite oxidation. For this, female pregnant Wistar rats were fed either normal or 50% of the normal intake diets during the whole gestational period. Male offspring (16 weeks of age) were studied to assess microvascular reactivity, superoxide production using a hydroethidine staining assay, nitric oxide synthase (NOS) activity and nitric oxide (NO) production. Western blot analysis was used to quantify nitrotyrosine-containing proteins and relative multiplex RT-PCR analysis for endothelial NOS (eNOS) mRNA expression. Superfusion with tetrahydrobiopterin significantly decreased superoxide generation and improved vascular function. Intrauterine malnutrition induced a decrement of NOS activity and NO production without affecting the gene expression of eNOS. However, incubation with tetrahydrobiopterin significantly improved NO production after stimulation with acetylcholine or bradykinin in intrauterine undernourished rats. The fact that the nitrotyrosine-containing proteins were increased could, at first sight, suggest that the peroxynitrite is the mediator responsible for the excessive oxidation and depletion of tetrahydrobiopterin. Our study shows that exogenous application of tetrahydrobiopterin leads to a significant improvement of endothelium-dependent vasodilatation, enhanced NO production and decreased superoxide generation in microvessels of intrauterine undernourished rats. Since we found a decrease in NOS activity without an alteration in the gene expression of eNOS, we suggest that impaired NOS-dependent responses of mesenteric arterioles are related to the impairment of tetrahydrobiopterin pathways.