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Abstract

The effect of intramammary (IMM) or intravenous (IV) administration of E. coli endotoxin (LPS), at the onset of estrus, at the time of ovulation was examined. Steroid and gonadotropin concentrations around ovulation were also determined. Lactating Holstein cows (n=33) were assigned to saline-controls (n=12) and treated with LPS-IV (0.5 microg/kg; n=13) or LPS-IMM (10 microg; n=8). Synchronized cows were observed continuously for estrus. LPS (or saline) was injected within 30 min from the onset of standing estrus, at peak estradiol concentrations. The typical rise of body temperature, somatic cell count, cortisol, and NAGase activity was noted. One-third of both LPS-IV- and LPS-IMM-treated cows were manifested by an extended estrus to ovulation (E-O) interval of around 75 h or did not ovulate, compared with about 30 h in the other 2/3 of LPS cows and all controls. Estradiol concentrations 24 h before and after LPS did not differ between groups. However, LPS-IV cows with extended intervals exhibited another estrus and an additional rise of estradiol followed by delayed ovulation. LPS-treated cows with a delayed E-O interval had low or delayed LH surge; two LPS-treated cows did not exhibit LH surge and did not ovulate. All control cows exhibited normal hormone levels. Delayed ovulation was associated with a delayed rise of luteal progesterone. The results indicated that exposing cows to endotoxin during estrus induced a decreased and delayed LH surge in one-third of the cows. This was associated with delayed ovulation, which reduces the chances of successful fertilization.

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... Either clinical or subclinical IMI caused by gram-positive or gram-negative bacteria pre or post insemination drops the conception rate [34]. In chronic cases of subclinical mastitis 30 percent of affected cows showed delayed ovulation [39]. ...
... Moreover, exposure of cows to endotoxin during estrus triggered a diminished and delayed luteinizing hormone (LH) surge in one-third of the cows which resulted in delayed ovulation and, ultimately, decreased the chances of successful fertilization [39]. ...
... for three weeks [46]. Thus, intra-mammary infections could promote delayed or absence of ovulation [39] which causes decreased fertility or infertility in dairy animals. ...
Article
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According to the international dairy federation, the dairy sector provides up to one billion livelihoods around the globe. Albeit, it faces many challenges including the two potentially threatening diseases which are mastitis and infertility. Both are complex multifactorial diseases, and mastitis is associated with causing infertility. Mastitis is an intramammary infection (IMI) and it occurs in two forms, clinical and subclinical. Mastitis being the infection of mammary glands, directly affects milk production to reduce its quality and quantity and indirectly hinders the reproductive performance of dairy animals. It negatively affects the reproduction parameters of dairy animals including, an increase in days open, a decrease in pregnancy rates, and increases chances of early embryonic losses and abortion. The chronic cases of mastitis lead toward the infertility of dairy animals and both of these diseases are responsible for increasing the culling rate and decreasing the profitability of a dairy farm. The objective of this study is to illustrate the influence of subclinical mastitis on reproduction parameters of dairy animals including, days open, days to the first service after calving, pregnancy rates, abortion, and embryonic losses. The relation between mastitis and infertility will be explained mechanistically.
... LPS-induced or naturally occurring clinical IMI is characterized by a transient surge of inflammatory mediators. Administration of LPS during the follicular phase [8] or at onset of estrus [10] delayed the preovulatory luteinizing hormone (LH) surge and ovulation in onethird of cows. Others have shown that LPS or cytokines depress steroid production in theca and granulosa cells [11,12]. ...
... The latter was not associated with any change in pulsatile LH or cortisol concentrations in subclinical IMI or past clinical IMI [13]. In contrast, disruption of estradiol secretion by acute exposure to endotoxin is associated primarily with depressed pulsatile LH secretion [8,16], which may be related to activation of the adrenal axis [10,17]. The above information suggests that the low estradiol level in one-third of subclinical IMI cows is not caused by altered secretion of LH pulses, but rather by the effect of one or more as yet unidentified inflammatory mediators capable of disrupting steroidogenesis. ...
... The proportion of one-third of IMI cows exhibiting susceptibility to IMI vs two-thirds showing normal reproductive responses has been observed, in 30 of a total of 96 experimental cows, in 4 independent studies ex-amining naturally occurring or induced subclinical or clinical IMI [10,13,37, and the current study]. This phenomenon therefore appears to hold for a broader population. ...
... Moreover, LPS can interrupt ovarian follicular development by adversely affecting the hypothalamus and inhibiting the release of gonadotropins (Suzuki et al.,2001;Williams et al., 2007). Mammary infections (mastitis) interrupt ovarian functions during the estrous cycle, decreasing follicular growth and estradiol (E2) levels, disrupting luteal activity, and resulting in compromised ovarian functions (Sheldon et al., 2002;Lavon et al., 2008). Long-term mechanisms including follicular growth and development can be affected by subclinical forms of mastitis (Lavon et al., 2011;Rahman et al., 2012 andRoth et al., 2013). ...
... Endotoxin that produced from gram negative bacterial infection (mastitis) caused a reduced and delayed LH surge in cows during estrus. This has been linked to a delay in ovulation, which lowers the probability of fertilization success (Lavon et al., 2008). Table (3) shows concentrations of progesterone and estradiol-17β during estrous cycle in cows with mastitis which were significantly (P < 0.05) lower compared to those in healthy cows. ...
... Suzuki et al. (2001) found that the basal LH pulsatility was disrupted, the plasma level of estradiol-17 was dramatically reduced, and the formation of the preovulatory LH peak was delayed or entirely blocked in heifers given an intravenous endotoxin (cytokines) like that produced by bacteria in mastitis infection. Mammary infections interrupt ovarian functions during the estrous cycle, decreasing follicular growth and estradiol (E 2 ) development, disrupting luteal activity, and resulting in compromised ovarian functions (Sheldon et al., 2002;Lavon et al., 2008). Intravenous infusion of lipopolysaccharides in bovine in granulosa cells of the dominant follicle, LPS reduces the expression of steroidogenic genes and modulates the expression of toll-like receptor 4 (TLR4) and tumor necrosis factor (TNF) (Campos et al., 2017). ...
... Use of the same type and dose of LPS used herein to induce mammary gland inammation showed signicant initial responses of elevated rectal temperature, heart rate, respiration rate and plasma cortisol concentration within 3-4 h; these responses peaked within 4-6 h and returned to pre-IMC levels at about 10 h post-treatment. 28 The LPS-IMC-induced an acute inammatory response in the treated gland was reected by elevation of SCC and activity of the lysosomal enzyme b-Nacetyl-D-glucosaminidase in milk. 12,28 LPS-IMC-induced elevation of SCC consisted mainly of leukocytes, mostly PMNs (CD18 + marked cells; Fig. 1). ...
... Based on previous studies, it is assumed that the vast majority of the reduction occurred in the treated gland. 12,28 This phenomenon is consistent with previous experiments in which the same dose and type of LPS were applied, resulting in a maximal decrease of $50% in milk yield, which was recorded 24 h post-treatment and $20% decrease at 48 h post-treatment. 12,28 At 96 h post-treatment, the reduction in milk yield resumed to pre-treatment levels (Fig. 3). ...
... 12,28 This phenomenon is consistent with previous experiments in which the same dose and type of LPS were applied, resulting in a maximal decrease of $50% in milk yield, which was recorded 24 h post-treatment and $20% decrease at 48 h post-treatment. 12,28 At 96 h post-treatment, the reduction in milk yield resumed to pre-treatment levels (Fig. 3). In previous studies 12, 28 and the current one, the reductions in milk yield were closely associated with a marked reduction of ...
Article
The concentrations of glucose and glucose-derived carbons in milk reflect their concentrations in the mammary epithelial cell cytosol. We hypothesized that the sharp reduction in milk secretion observed during acute inflammation in the mammary gland is associated with conversion of the gland’s metabolism to aerobic glycolysis and reduced extraction of glucose from the blood, in support to the innate immune system. Acute inflammation was induced by challenging one mammary gland in 5 cows with a single dose of 10 μg bacterial lipopolysaccharide. The glandular response was followed up to 96 h post-challenge. The challenge induced increases in polymorphonuclear leukocytes, milk malonyldialdehyde concentration and casein degradation. The response peaked at 24 h post-challenge and the inflammation began to decrease after 48 h, but at 96 h post-treatment, values had not yet returned to pre-treatment levels. Milk secretion, and milk lactose, glucose and citrate concentrations decreased sharply, reaching minimal levels at 24 h post-treatment. The correlations between these parameters and inflammation parameters were negative and statistically significant. The reduction of ~50% in milk yield and lactose concentration in the treated gland indicated that extraction of glucose from the blood was reduced from a rate of ~740 g/d to 190 g/d (i.e., by 550 g/d) at the peak of response. The concentrations of glucose-6-phosphate, malate, oxaloacetate, lactate and pyruvate and the activities of the enzymes glucose-6-phosphate dehydrogenase, malate dehydrogenase and lactate dehydrogenase increased and, in general, were positively and significantly correlated to inflammation parameters. It was concluded that inflammation shifts the passage of glucose-derived carbons to the pentose phosphate pathway and shifts cell metabolism to glycolysis at the expense of mitochondrial activity.
... The mRNA levels of interleukin (IL)-1, IL-6, IL-8, and interferon-alpha increase in porcine T-cells infected with FMDV [12]. In addition, anovulation has been confirmed to be an inflammation model by directly injecting lipopolysaccharide (LPS) into ovarian follicles and by intravenous injection in cattle [13,14]. The expression of genes related to the acute-phase immune response, such as steroidogenic acute regulatory protein, Tolllike receptor 4, and tumor necrosis factor alpha (TNF-α), decreases significantly upon intravenous LPS injection [13]. ...
... The increase in inflammatory cytokines in response to FMDV vaccines reduces 17β-estradiol (E2) and increases prostaglandin F2α (PGF2α) and body temperature [8, 11,15]. Previous studies have reported that ovulation is delayed due to a relative decrease in progesterone (P4) and luteinizing hormone (LH) due to the imbalance between E2 and P4 [11,14]. ...
... Ferreira et al. reported that rectal temperature increases in cows after FMDV vaccine administration, and our ruminal temperature results were similar [8,21]. Body temperature rises more rapidly than usual within~4 h after LPS injection in the direct intravenous injection model [14]. In addition, the imbalance in major ovulatory hormones, such as P4, E2, and LH, is accompanied by an acute-phase immune response to the FMDV vaccine [8, 11,14]. ...
Article
Full-text available
Vaccination against foot-and-mouth disease is the most common method for preventing the spread of the disease; the negative effects include miscarriage, early embryo death, lower milk production, and decreased growth of fattening cattle. Therefore, in this study, we analyze the side effects of vaccination by determining the acute immune response and ovulation rate after vaccinating cows for foot-and-mouth disease. The test axis was synchronized with ovulation using 100 Hanwoo (Bos taurus coreanae) cows from the Gyeongsangbuk-do Livestock Research Institute; only individuals with estrus confirmed by ovarian ultrasound were used for the test. All test axes were artificially inseminated 21 days after the previous estrus date. The control group was administered 0.9% normal saline, the negative control was injected intramuscularly with lipopolysaccharide (LPS; 0.5 µg/kg), and the test group was administered a foot-and-mouth disease virus vaccine (FMDV vaccine; bioaftogen, O and A serotypes, inactivated vaccine) 2, 9, and 16 days before artificial insemination. White blood cells and neutrophils increased significantly 1 day after vaccination, and body temperature in the rumen increased for 16 h after vaccination. Ovulation was detected 1 day after artificial fertilization by ovarian ultrasound. The ovulation rates were as follows: control 89%, LPS 60%, FMDV vaccine (-2 d) 50%, FMDV vaccine (-9 d) 75%, and FMDV vaccine (-16 d) 75%. In particular, the FMDV vaccine (-2 d) test group confirmed that ovulation was delayed for 4 days after artificial insemination. In addition, it was confirmed that it took 9 days after inoculation for the plasma contents of haptoglobin and serum amyloid A to recover to the normal range as the main acute immune response factors. The conception rate of the FMDV vaccine (-2 d) group was 20%, which was significantly lower than that of the other test groups.
... Likewise, decreased steroid production capacity in the POF of dairy cattle with either clinical or subclinical mastitis has been reported previously (Lavon et al., 2011a(Lavon et al., , 2011b. Besides, several reports in dairy cattle have also indicated that conception rates are lowered by clinical or subclinical mastitis occurring before AI (Hertl et al., 2010;Lavon et al., 2008;Santos et al., 2004) induction of CM before AI during the follicular phase caused a significant reduction of pulsatile luteinizing hormone (LH) secretion, subsequently inducing low secretion of estradiol close to estrus, and delayed LH surge and ovulation (Hockett et al., 2005;Lavon et al., 2008). ...
... Likewise, decreased steroid production capacity in the POF of dairy cattle with either clinical or subclinical mastitis has been reported previously (Lavon et al., 2011a(Lavon et al., , 2011b. Besides, several reports in dairy cattle have also indicated that conception rates are lowered by clinical or subclinical mastitis occurring before AI (Hertl et al., 2010;Lavon et al., 2008;Santos et al., 2004) induction of CM before AI during the follicular phase caused a significant reduction of pulsatile luteinizing hormone (LH) secretion, subsequently inducing low secretion of estradiol close to estrus, and delayed LH surge and ovulation (Hockett et al., 2005;Lavon et al., 2008). ...
Article
The objectives of this study was to investigate the outcome of mastitis, in its clinical or subclinical forms, on the mean diameter of pre-ovulatory follicle (POF), plasma estradiol concentration on the day of estrus, subsequent luteal profile and subsequent conception rate in buffaloes. Sixty dairy buffalo (Bubalus bubalus) conducted in this study were divided into three groups {healthy (H), n=20; subclinical mastitis (SCM), n=18; and clinical mastitis (CM), n=22}. Ultrasonography of ovaries revealed that mean diameter of POF was larger (P<0.05) in H buffalo (14.35mm) compared to SCM (12.40mm) and CM (10.25mm). Also, plasma estradiol concentration on the day of estrus was higher (P<0.05) in H buffalo compared to SCM and CM counterparts; 34.95 vs. 32.87 and 27.50pg/ml, respectively. Besides, positive correlation was observed between the POF diameter with plasma estradiol concentration in H, SCM and CM buffaloes (r=0.64, 0.74, 0.72 respectively, P<0.05). Moreover, positive correlations (P<0.01) were found on days 9, 12, 16, and 21 post-ovulation between POF diameter and luteal profile. Thus, the conception rate in H buffalo was higher (P<0.05) compared with SCM and CM counterparts; 55% vs. 38.89 and 18.18%, respectively. In conclusion, mastitis in its clinical or subclinical forms disrupts the functioning of the pre-ovulatory follicle on the day of estrus, associated with low follicular estradiol production, resulting in suppression to subsequent luteal profile leading to substantial decrease in pregnancy consequence of buffaloes.
... Indeed, several studies showed that the exact time of exposure to the endotoxin prior to the LH surge is important for delayed ovulation (Battaglia et al. 2000;Breen et al. 2004). Lavon et al. (2008) studied the effects of intramammary or intravenous administration of LPS during estrus or at the time of ovulation on reproductive function. They reported that the LH surge was delayed in cows exposed to LPS during estrus resulting in delayed ovulation (delayed estrus-ovulation interval from 30 to 75 h), which ultimately reduced the chances of successful fertilization. ...
... uberis was also reported in cattle (Hockett et al. 2000). Lavon et al. (2008) suggested that the level of milk yield, the body condition score, the stage of lactation, as well as the extent of increased milk somatic cell count (SCC), body temperature, heart rate, and respiratory rate as possible reasons for variation after LPS infusion. Asaf et al. (2013) found a differential disruptive effect of mastitis induced by gram-negative and gram-positive pathogens on oocyte developmental competence along with alterations in maternal gene expression. ...
Article
Full-text available
The reproductive performance of dairy animals is influenced by several factors, and accumulating lines of evidence indicate that mastitis is one of the determinants. Most of the published information relating mastitis with reproduction has evolved based on retrospective approach rather than controlled clinical studies. The complex nature of both mastitis and reproduction could be a limiting factor for understanding their relationship in detail. In this review, we analyzed the available retrospective studies on the effects of clinical mastitis on reproductive function and explained the possible mechanisms by which mastitis affects reproduction in dairy animals.
... Several studies have shown a reduction in follicular steroid production in response to clinical, short-term, acute mastitis (natural or induced). Intramammary infusion of endotoxin (LPS) or inoculation with E coli resulted in an immediate disruptive effect on follicular function [56,57]. Proinflammatory cytokines have been suggested to underlie these effects. ...
... Attenuation of estradiol production by interferon gamma and reduction of CYP19A1 activity by IL-6 have been documented [58][59][60]. The immediate decrease in steroidogenesis induced by E coli LPS could also be related to activation of the adrenal system, which in turn may induce suppression of pulsatile LH secretion as a primary effect, consequently leading to decreased estradiol and LH-surge secretions and delayed ovulation [33,56,61]. ...
... However, excess inflammation can also be detrimental to fertility. For example, metritic cows (Dohmen et al., 2000;Mateus et al., 2003) are less fertile (Sheldon et al., 2014), likely because LPS alters steroid signaling (Kujjo et al., 1995;Lavon et al., 2008), compromises caprine luteal function (Fredriksson et al., 1985;Gilbert et al., 1990), and causes abortion (Skarnes and Harper, 1972;Giri et al., 1990). Estrogen sulfotransferase (SULT1E1) is a transcriptional target of phosphorylated nuclear factor kappa B, and in mice, LPS induces SULT1E1 (Chai et al., 2015). ...
... Interestingly, Kahl et al. (2011) report that pre-treating steers with exogenous E2 enhanced the pro-inflammatory response to an LPS bolus, suggesting that E2 augments inflammation. Cows injected i.v. with LPS at the onset of estrus have longer estrus to ovulation windows or inhibition of ovulation entirely, and increased E2 was reported before delayed ovulation (Lavon et al., 2008). Chai et al. (2015) demonstrated that LPS induces hepatic expression of SULT1E1, a deactivator of estrogens (Song, 2001), and that SULT1E1 is a transcriptional target of NFκB. ...
Article
Lipopolysaccharide (LPS) administration causes immunoactivation, which negatively affects production and fertility, but experimental exposure via an acute bolus is unlikely to resemble natural infections. Thus, the objectives were to characterize effects of chronic endotoxemia on production parameters and follicular development in estrous-synchronized lactating cows. Eleven Holstein cows (169 ± 20 d in milk; 681 ± 16 kg of body weight) were acclimated to their environmental surroundings for 3 d and then enrolled in 2 experimental periods (P). During P1 (3 d) cows consumed feed ad libitum and baseline samples were obtained. During P2 (7 d), cows were assigned to continuous infusion of either (1) saline-infused and pair-fed (CON-PF; 40 mL/h of saline i.v.; n = 5) or (2) LPS infused and ad libitum fed (LPS-AL; Escherichia coli O55:B5; 0.017, 0.020, 0.026, 0.036, 0.055, 0.088, and 0.148 μg/kg of body weight/h i.v. on d 1 to 7, respectively; n = 6). Controls were pair-fed to the LPS-AL group to eliminate confounding effects of dissimilar nutrient intake. Infusing LPS temporally caused mild hyperthermia on d 1 to 3 (+0.49°C) relative to baseline. Dry matter intake of LPS-AL cows decreased (28%) on d 1 of P2, then progressively returned to baseline. Relative to baseline, milk yield from LPS-AL cows was decreased on d 1 of P2 (12%). No treatment differences were observed in milk yield during P2. Follicular growth, dominant follicle size, serum progesterone (P4), and follicular P4 and 17β-estradiol concentrations were similar between treatments. Serum 17β-estradiol tended to increase (115%) and serum amyloid A and LPS-binding protein were increased (118 and 40%, respectively) in LPS-AL relative to CON-PF cows. Compared with CON-PF, neutrophils in LPS-AL cows were initially increased (45%), then gradually decreased. In contrast, monocytes were initially decreased (40%) and progressively increased with time in the LPS-AL cows. Hepatic mRNA abundance of cytochrome P450 family 2 subfamily C (CYP2C) or CYP3A was not affected by LPS, nor was there a treatment effect on toll-like receptor 4 or LBP; however, acyloxyacyl hydrolase and RELA subunit of nuclear factor kappa B tended to be increased in LPS-AL cows. These data suggest lactating dairy cows become tolerant to chronic and exponentially increasing LPS infusion in terms of production and reproductive parameters.
... Rectal temperature, and cardiac and respiratory frequencies did not change in heifers during intrauterine LPS challenge. In contrast, these parameters increased after intravenous (0.5 µg/kg of BW; Lavon et al., 2008;Herzog et al., 2012) and intramammary LPS applica-tion (10 µg/cow; Lavon et al., 2008), indicating that the endometrium is less sensitive to local LPS challenge with regard to the induction of a systemic immune response. Moreover, plasma concentrations of cortisol, which is a good index of stress in cattle (Mudron et al., 2007;Mosher et al., 2013), and haptoglobin, an acute phase protein that is released during the innate immune response to inflammation (Murata et al., 2004), were similar in the LPS and the CON cycle. ...
... Rectal temperature, and cardiac and respiratory frequencies did not change in heifers during intrauterine LPS challenge. In contrast, these parameters increased after intravenous (0.5 µg/kg of BW; Lavon et al., 2008;Herzog et al., 2012) and intramammary LPS applica-tion (10 µg/cow; Lavon et al., 2008), indicating that the endometrium is less sensitive to local LPS challenge with regard to the induction of a systemic immune response. Moreover, plasma concentrations of cortisol, which is a good index of stress in cattle (Mudron et al., 2007;Mosher et al., 2013), and haptoglobin, an acute phase protein that is released during the innate immune response to inflammation (Murata et al., 2004), were similar in the LPS and the CON cycle. ...
Article
Inflammation of the uterus is associated with disturbed ovarian function and reduced reproductive performance in dairy cows. To investigate the influence of endometritis on the bovine corpus luteum, 8 heifers received intrauterine infusions with either phosphate-buffered saline (PBS; 9 mL) or Escherichia coli lipopolysaccharide (LPS; 3 µg/kg of body weight diluted in 9 mL of PBS) at 6-h intervals from 12 h before and until 9 d after ovulation during 2 cycles in a random order (ovulation = d 1). An untreated cycle was examined before and after PBS and LPS cycles, and the mean values from both untreated cycles were used as control. In all cycles, blood sampling and ultrasonography of the ovaries were performed on d 0, 1, 2, 4, 6, 8, 9, 10, 12, 15, 18, and then every 2 d until ovulation. Endometrial cells were collected for cytology and quantitative real-time reverse transcriptase PCR on d 0, 6, and 9, and on d 0 and 6, respectively, and luteal tissue was collected for quantitative real-time reverse transcriptase PCR on d 6 and 9. Both, PBS and LPS infusions induced subclinical endometritis, which was accompanied by increased endometrial mRNA abundance of proinflammatory cytokines IL1β, IL8, and tumor necrosis factor α. Additionally, LPS challenge induced premature luteolysis, which was characterized by increased plasma concentrations of PGF2α metabolite, decreased plasma progesterone concentrations, and reduced luteal size and blood flow compared with the control. The luteal mRNA expression of the LPS receptor TLR4, PGE synthase, and the apoptosis-related factor CASP3 were higher, and those of steroidogenic factors STAR and HSD3B, the PGF receptor, and the angiogenic factor VEGFA121 were lower after LPS challenge compared with the control. In conclusion, repeated intrauterine LPS infusions during the first 9 d of the estrous cycle alter gene expression and shorten the lifespan of the bovine corpus luteum.
... Epidemiological studies have shown that fertility of mastitic cows is lower than that of uninfected cows [2,4e6]. Other studies have reported that mastitis associated with increased interval (days) from parturition to first AI increases the number of services for conception [1,7], and impairs ovulation [8,9]. Accumulated evidence suggests a deleterious effect of mastitis on the hypothalamicepituitaryeovarian axis [10], expressed as impaired follicular development and steroidogenesis [11,12]. ...
... Following careful cleaning of the teat, intramammary administration was performed 36 h after the additional PGF 2a treatment (i.e., 6 h before FF aspiration), using a sterile syringe mounted with a sterile adapter via the nipple canal, as previously described [9]. Control cows (n ¼ 3; Saline) received 10 mL of sterile nonpyrogenic saline; treated cows (n ¼ 3; LPS) received 10 mg LPS (E. coli O55:B5, Sigma Chemical Co., St. Louis, MO, USA) dissolved in 10 mL nonpyrogenic saline. ...
Article
Mastitis has deleterious effects on ovarian function and reproductive performance. We studied the association between plasma or follicular fluid (FF) obtained from endotoxin-induced mastitic cows, and oocyte developmental competence. Lactating Holstein cows were synchronized using the Ovsynch protocol. On Day 6 of the synchronized cycle, an additional PGF2α dose was administered, and either Escherichia coli endotoxin (LPS, 10 μg; n = 3 cows) or saline (n = 3 cows) was administered to one udder quarter per cow, 36 h later. Milk samples were collected and rectal temperatures recorded. Cows treated with LPS showed a typical transient increase in body temperature (40.3 °C ± 0.4), whereas cows treated with saline maintained normal body temperature (38.9 °C ± 0.04). A higher (P < 0.05) somatic cell count was recorded for cows treated with LPS. Plasma samples were collected and FF was aspirated from the preovulatory follicles by transvaginal ultrasound probe, 6 h after LPS administration. Radioimmunoassay was performed on plasma samples to determine estradiol and cortisol concentrations. Either FF or plasma was further used as maturation medium. In the first experiment, oocytes were matured in TCM-199 (Control) or in FF aspirated from cows treated with saline (FF-Saline) or LPS (FF-LPS). Cleavage rate to the 2- to 4-cell stage embryo did not differ among groups. However, the proportion of developed blastocysts on Day 7 postfertilization in the FF-LPS group tended to be lower for that in FF-Saline and was lower (P < 0.05) than that in the Control groups (10.6 vs. 22.4 and 24.4%, respectively). In the second experiment, oocytes were matured in TCM-199 (Control), or in plasma obtained from cows treated with saline (Plasma-Saline) or LPS (Plasma-LPS). Similar to the FF findings, cleavage rate did not differ among groups; however, the proportion of developing blastocysts tended to be lower in the Plasma-LPS group than in the Plasma-Saline group and was lower (P < 0.05) from that in the Control group (11.0 vs. 25.5 and 34.7%, respectively). The proportion of apoptotic cells per blastocyst, determined by TUNEL assay, did not differ among the experimental groups. The findings shed light on the mechanism by which mastitis induces a disruption in oocyte developmental competence. Further studies are required to clarify whether the negative effect on oocyte developmental competence is a result of LPS, by itself, or due to elevation of secondary inflammatory agents.
... Mastitis, an inflammation of the mammary gland that often results from bacterial infection, is regarded as the most prevalent disease in dairy cattle (Lavon et al., 2008). Apart from local inflammation of the mammary tissue, mastitis exerts varied systemic effects (Bannerman et al., 2004). ...
... The cytokine IFN-α is able to inhibit the release of the LH from the pituitary (Barros et al., 1992), which leads to anovulation or delayed ovulation in cows. Consistently, the intravenous or intramammary administration of LPS delays ovulation due to decreased LH surges (Lavon et al., 2008). Other cytokines that are enhanced due to mastitis can exert direct effects on the ovary. ...
Article
Data from various studies indicate that the ovarian function in dairy cows can be compromised during intramammary infections. Therefore, in this study, we investigated if an experimentally induced mastitis has an effect on corpus luteum (CL) function in 14 lactating cows. On d 9 of the estrous cycle (d 1 = ovulation), cows received a single dose of 200 μg of Escherichia coli lipopolysaccharide (LPS; dissolved in 10 mL of NaCL; n = 8) or 10 mL of saline (control; n = 6) into one quarter of the mammary gland. Measurements included plasma cortisol, haptoglobin, and progesterone (P4) concentrations, as well as luteal size (LTA) and relative luteal blood flow (rLBF). Sampling was performed on d 1, 4, and 8. On d 9, the main examination day, sampling was performed immediately before (0 h), every 1 h (or at 3-h intervals for LTA and rLBF) until 9 h, as well as 12 and 24 h after treatment. Thereafter, measurements were taken on d 12, 15, 18, and then every 2 d until ovulation. Luteal tissue was collected for biopsy 24 h before and 6 h after treatment. Quantitative real-time PCR was applied to assess mRNA expression of steroidogenic factors (STAR, HSD3B), caspase 3, toll-like receptors (TLR2, -4), tumor necrosis factor α (TNFA), and prostaglandin-related factors (PGES, PGFS, PTGFR). Intramammary LPS infusion caused considerable inflammatory responses in the treated udder quarters. No decrease in plasma P4 concentrations was noted after LPS-challenge, and P4 levels did not differ between LPS-treated and control cows. Furthermore, LTA and rLBF values were not decreased after LPS challenge compared with the values obtained immediately before treatment. However, LPS infusion increased plasma levels of cortisol and haptoglobin compared with the control group. In the CL, mRNA abundance of TLR2 and TNFA was increased in cows after LPS-challenge (but not in control cows), whereas TLR4, steroidogenic, and prostaglandin-related factors remained similar to the mRNA abundance before treatment. In conclusion, intramammary LPS challenge induces systemic inflammatory reactions which alter the luteal mRNA abundance of TLR2 and TNFA but does not induce lysis of the CL.
... Likewise, decreased steroid production capacity in the POF of dairy cattle with either clinical or subclinical mastitis has been reported previously (Lavon et al., 2011a(Lavon et al., , 2011b. Besides, several reports in dairy cattle have also indicated that conception rates are lowered by clinical or subclinical mastitis occurring before AI (Hertl et al., 2010;Lavon et al., 2008;Santos et al., 2004) induction of CM before AI during the follicular phase caused a significant reduction of pulsatile luteinizing hormone (LH) secretion, subsequently inducing low secretion of estradiol close to estrus, and delayed LH surge and ovulation (Hockett et al., 2005;Lavon et al., 2008). ...
... Likewise, decreased steroid production capacity in the POF of dairy cattle with either clinical or subclinical mastitis has been reported previously (Lavon et al., 2011a(Lavon et al., , 2011b. Besides, several reports in dairy cattle have also indicated that conception rates are lowered by clinical or subclinical mastitis occurring before AI (Hertl et al., 2010;Lavon et al., 2008;Santos et al., 2004) induction of CM before AI during the follicular phase caused a significant reduction of pulsatile luteinizing hormone (LH) secretion, subsequently inducing low secretion of estradiol close to estrus, and delayed LH surge and ovulation (Hockett et al., 2005;Lavon et al., 2008). ...
... A systemic inflammatory response due to bovine metritis and mastitis is often associated with the presence of lipopolysaccharide (LPS), the endotoxin of gramnegative bacteria (Bannerman et al. 2004, Williams et al. 2005). There is increasing evidence that, at least in part, Escherichia coli LPS causes infertility by interfering with ovarian function (Suzuki et al. 2001, Lavon et al. 2008). Ovarian dysfunction due to LPS in cows with inflammatory diseases might be due to impairment of the hypothalamic-pituitary axis and interference with ovarian follicular and luteal function (Hansen et al. 2004 ). ...
... LPS was found in the follicular fluid of such animals, likely additionally contributing to the delay in ovulation (Sheldon et al. 2009b). Similar effects associated with a delayed luteinizing hormone surge and the resulting postponed ovulation were observed after intravenous or intramammary administration of LPS in cows (Lavon et al. 2008). Furthermore, intravenous treatment with LPS transiently suppressed progesterone (P 4 ) secretion by the bovine corpus luteum (CL) and increased plasma concentrations of prostaglandin (PG) F 2a metabolites (PGFM) (Herzog et al. 2012). ...
Article
When given intravenously (iv), lipopolysaccharide (LPS) transiently suppresses the structure and function of the bovine corpus luteum (CL). This is associated with increased release of prostaglandin (PG) F2α metabolite (PGFM). The underlying regulatory mechanisms of this process remain, however, obscure. Therefore, the aims of this study were: (1) to investigate the expression of the LPS receptor toll-like receptor (TLR) 4 and TLR2 in the bovine CL during early, mid, and late luteal phases; (2) to further dissect the mechanisms of LPS-mediated suppression of luteal function. As revealed by semi-quantitative qPCR and immunohistochemistry, both receptors were detectable throughout the luteal lifespan. Their mRNA levels increased from the early towards the mid-luteal phase; no further changes were observed thereafter. The TLR4 protein seemed more highly represented than TLR2. The cellular localization of TLRs was in blood vessels; weaker signals were observed in luteal cells. Additionally, cows were treated either with LPS (iv, 0.5 µg/kgBW) or with saline on Day 10 after ovulation. Samples were collected 12 h after treatment, and on Day 10 of the respective subsequent (untreated) cycle. The mRNA expression of several possible regulatory factors was investigated, revealing the suppression of PGF2α receptor (PTGFR), steroidogenic acute regulatory protein (STAR) and 3β-hydroxysteroid dehydrogenase (3βHSD), compared with controls and subsequent cycles. The expression of TLR2 and TLR4, interleukin (IL) 1α and IL1β, and of PGF2α and PGE2 synthases (20αHSD/PGFS and mPTGES, respectively) was increased. The results demonstrate the presence of TLR2 and TLR4 in the bovine CL, and implicate their possible involvement in the deleterious effects of LPS on its function.
... Another study showed that LPS causes a decline in CL size and a decrease in plasma progesterone level (Herzog et al., 2012). In contrast, intramammary administration of LPS at the onset of estrus did not cause early luteal regression and did not induce decline of progesterone concentrations (Lavon et al., 2008). The effect of G+ bacteria on luteal function is also debatable. ...
... As with the effect of IMI on the CL, distinguishing between clinical and subclinical mastitis is important. For instance, induction of clinical mastitis before AI during the follicular phase caused a significant reduction of pulsatile luteinizing hormone (LH) secretion, subsequently inducing low secretion of estradiol close to estrus, and delayed LH surge and ovulation (Hockett et al., 2005;Lavon et al., 2008). However, in those studies, an acute, short-term, experimental pathogenic stress was induced by intramammary administration of endotoxin or inoculation with bacteria. ...
Article
Mastitis (intramammary infection) causes the deterioration of ovarian follicular responses in cows, resulting in low fertility. The shortterm, acute clinical form of mastitis has a time-dependent disruptive effect on conception rate. It effectively lowers conception rate if events occur mainly 10 days before to 30 days after artificial insemination. Long-term subclinical mastitis is widely spread in commercial herds. Although it is less severe than clinical mastitis, its long-term nature causes a more pronounced decrease in conception rate. Even mild elevation of somatic cell count in subclinical cows significantly lowers conception rate. Disrupted follicular responses include depression of steroid production in the preovulatory follicle associated with low and delayed preovulatory luteinizing hormone surge, resulting in delayed ovulation in onethird of subclinical cows. Mastitis, clinical and subclinical, also impairs oocyte competence, reflected in low production of blastocysts. The corpus luteum seems to be insensitive to mastitis, possible due to the use of non-steroidal anti-inflammatory drugs when mastitis is first diagnosed.
... These molecules have the potential to disrupt GnRH and LH secretion, oocyte developmental competence, and embryonic survival in cattle (Hansen et al., 2004). Studies infusing lipopolysaccharide in the uterus, mammary gland, or intravenously, resulted in reduced secretion of GnRH and LH (Peter et al., 1989;Lavon et al., 2008). Incubation of granulosa cells with lipopolysaccharide or tumour necrosis factor (TNF) α resulted in smaller production of estradiol (Williams et al., 2008). ...
Article
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Inflammatory diseases are prevalent in cattle and impair fertility. Cows affected by inflammatory disease from parturition to the day before breeding have reduced fertilization of oocytes, reduced survival of zygotes to the morula stage, impaired development to early stages of conceptus elongation, reduced secretion of interferon during the period of pregnancy recognition, altered transcriptome of preimplantation conceptus cells, and increased pregnancy loss. Consequently, these cows have reduced pregnancy and calving per breeding. Reduced oocyte competence is a likely reason for the carryover effects of diseases on developmental biology, but impaired uterine environment is also involved. Effects on pregnancy survival are observed up to 5 months after the diagnosis and treatment of disease, and effects on developmental biology seem to be extended into postnatal life in pregnancies that survive until term. Although the biological mechanism mediating the effects of inflammatory diseases are still not completely understood, control of inflammation during the clinical presentation of diseases seems to alleviate the negative effects on reproductive biology. It is increasingly evident that animal health, not only at the time of breeding or pregnancy development but also in the period preceding breeding, is imperative for optimal reproduction in cattle and should always be considered in herd evaluations and managerial decisions.
... Intramammary injections were performed following careful cleaning of the teat, using a sterile syringe mounted with a sterile adapter via the teat canal into the gland, as described previously (Lavon et al. 2008). Clinical symptoms such as swelling, rigidity, and high sensitivity of the udder were checked frequently throughout the day of administration. ...
... In most dairy cows, these contaminations are gradually eliminated by 6 weeks after calving, but in 10-15 % of cows infection persists and impairs utero-ovarian function (Borsberry and Dobson 1989;Vanholder et al. 2006). Uterine infections may disrupt luteinizing hormone (LH) surge and subsequently ovulation directly through production of endotoxin (Suzuki, et al. 2001;Lavon et al. 2008) and indirectly by stimulation of leukocytes to secrete inflammatory mediators (Williams et al. 2008), adrenal gland to produce cortisol (Peter et al. 1989(Peter et al. , 1990Breen and Karsch, 2004), and perturbation of follicular steroidogenesis (Herath et al. 2007). Cows with a high bacterial growth density of the uterus have a smaller dominant follicle and decreased plasma estradiol concentrations (Sheldon et al. 2002). ...
Article
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The present study aimed to determine the relationships among uterine bacterial infection, ovarian cysts, and endometritis. A total of 21 genital tracts with ovarian cysts were collected from the abattoir. Cystic fluids were aspirated from ovarian cysts (follicular cysts, n = 10; luteal cysts, n = 11) and eight large follicles (<15 mm) with clear appearance as control for hormone assay. Samples from the internal surface of the uterine body, right and left uterine horns were collected and cultured for bacteriological examinations. In addition, samples from the cystic walls, uterine horns, and bodies were subjected to histopathological examinations. E2/P4 ratio was higher in follicular fluid in cows without ovarian cysts but with endometritis than that of cows with both ovarian cysts and endometritis (3.47 ± 1.37; 0.25 ± 0.11, p = 0.004). Further, cows that had endometritis and no ovarian cyst had a higher E2/P4 ratio than those of endometritic cows with either follicular cyst (3.47 ± 1.37; 0.51 ± 0.17, p = 0.03) or luteal cyst (3.47 ± 1.37; 0.003 ± 0.002, p = 0.01). As the E2/P4 ratio increased, the numbers of isolated bacterial species decreased from nine to one species of bacterial isolates. In conclusion, as the E2/P4 ratio increased in the follicular fluid, the numbers and diversity of bacterial species significantly decreased irrespective of pathogenicity of the uterine bacteria.
... The inflammatory mediators produced by the injured tissues and liver can also reach the reproductive tract, including ovaries and uterus, but also the brain, which influences the physiological processes that control normal reproductive cycles. Studies in which LPS was infused into the uterus, mammary gland, or intravenously resulted in reduced secretion of LH (Peter et al., 1989;Lavon et al., 2008). Cows that suffered from uterine disease postpartum had delayed growth of the first dominant follicle postpartum and reduced concentrations of estradiol (Sheldon et al., 2002). ...
Article
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The objective of this series of studies was to investigate the effects of inflammatory diseases occurring before breeding on the developmental biology and reproductive responses in dairy cows. Data from 5 studies were used to investigate different questions associating health status before breeding and reproductive responses. Health information for all studies was composed of the incidence of retained fetal membranes, metritis, mastitis, lameness, and respiratory and digestive problems from parturition until the day of breeding. Retained placenta and metritis were grouped as uterine disease (UTD). Mastitis, lameness, digestive and respiratory problems were grouped as nonuterine diseases (NUTD). Study 1 evaluated the effect of disease before artificial insemination (AI), anovulation before synchronization of the estrous cycle, and low body condition score at AI on pregnancy per AI, as well as their potential interactions or additive effects. Study 2 investigated the effect of site of inflammation (UTD vs. NUTD) and time of occurrence relative to preantral or antral stages of ovulatory follicle development, and the effect of UTD and NUTD on fertility responses of cows bred by AI or by embryo transfer. Study 3 evaluated the effect of disease on fertilization and embryonic development to the morula stage. Study 4 evaluated the effect of disease on preimplantation conceptus development as well as secretion of IFN-τ and transcriptome. Study 5 investigated the effect of diseases before AI on the transcript expression of interferon-stimulated genes in peripheral blood leukocytes during peri-implantation stages of conceptus development after first AI postpartum. Altogether, these studies demonstrated that inflammatory disease before breeding reduced fertilization of oocytes and development to morula, and impaired early conceptus development to elongation stages and secretion of IFN-τ in the uterine lumen. Diseases caused inflammation-like changes in transcriptome of conceptus cells, increased risk of pregnancy loss, and reduced pregnancy or calving per breeding. Moreover, the effects on reproduction were independent of cyclic status before synchronization of the estrous cycle and body condition score at breeding, which all had additive negative effects on fertility of dairy cows. Occurrence of disease at preantral or at antral stages of ovulatory follicle development had similar detrimental effects on pregnancy results. The carryover effects of diseases on developmental biology might last longer than 4 mo. Reduced oocyte competence is a likely reason for carryover effects of diseases on developmental biology, but impaired uterine environment was also shown to be involved.
... Furthermore, instillation of LPS in the mammary gland consistently increases systemic concen- trations of cytokine tumor necrosis factor alpha (TNFA; Blum et al. 2000). In addition, exogenous LPS reduced fertility due to impairment of ovarian follicular develop- ment and ovulation (Suzuki et al. 2001, Lavon et al. 2008, Williams et al. 2008). The LH peak was significantly retarded or completely inhibited in cows given LPS during proestrus (Suzuki et al. 2001). ...
Article
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Lipopolysaccharide (LPS), the endotoxin of gram-negative bacteria, has detrimental effects on structure and function of the bovine corpus luteum (CL) in vivo. The objective was to investigate whether these effects were mediated directly by LPS or via LPS-induced release of PGF2α. Bovine ovaries with a mid-cycle CL were collected immediately after slaughter and isolated perfused for 240 min. After 60 min of equilibration, LPS (0.5 μg/mL) was added to the medium of five ovaries, whereas an additional six ovaries were not treated with LPS (control). After 210 min of perfusion, all ovaries were treated with 500 iu of hCG. In the effluent perfusate, concentrations of progesterone (P4) and PGF2α were measured every 10 and 30 min, respectively. Punch biopsies of the CL were collected every 60 min and used for RT-qPCR to evaluate mRNA expression of receptors for LPS (TLR2, -4) and LH (LHCGR), the cytokine TNFA, steroidogenic (STAR, HSD3B), angiogenic (VEGFA121, FGF2) and vasoactive (EDN1) factors, and factors of prostaglandin synthesis (PGES, PGFS, PTGFR) and apoptosis (CASP3, -8, -9). Treatment with LPS abolished the hCG-induced increase in P4 (P≤0.05); however, there was only a tendency (P=0.10) for increased release of PGF2α at 70 min after LPS challenge. Furthermore, mRNA abundance of TLR2, TNFA, CASP3, CASP8, PGES, PGFS, and VEGFA121 increased (P≤0.05) after LPS treatment, whereas all other factors remained unchanged (P>0.05). In conclusion, reduced P4 responsiveness to hCG in LPS-treated ovaries in vitro was not due to reduced steroidogenesis, but was attributed to enhanced apoptosis. However, an impact of luteal PGF2α could not be excluded.
... However, experimental uterine LPS exposure (Peter et al., 1989;Karsch et al., 2002). Furthermore, ovulation is delayed in cows following systemic or intramammary administration of LPS, although GnRH has been used therapeutically to induce normal ovarian cyclicity in these animals (Suzuki et al., 2001;Lavon et al., 2008). The specific mechanisms by which LPS exposure at a distant site affects hypothalamic-pituitary function have yet to be elucidated; experimental models of systemic LPS administration (described previously) indicate the possibility of LPS entering the circulation and traveling to the brain, although it is interesting that blockade of TLR4 signaling seems to prevent LPS-induced GnRH-LH signal disruption (Haziak et al., 2014). ...
Article
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Uterine contamination with bacteria is ubiquitous in the postpartum dairy cow. Nearly one-half of all postpartum dairy cows develop clinical disease resulting in metritis and endometritis, which cause depressed milk production and infertility. The causative links between uterine infection and infertility include a hostile uterine environment, disrupted endocrine signaling, and perturbations in ovarian function and oocyte development. In this review we consider the various mechanisms linking uterine infection with infertility in the dairy cow, specifically 1) innate immune signaling in the endometrium, 2) alteration in endocrine signaling in response to infectious agents, and 3) impacts of infection on ovarian function, oocyte development, and follicular development. Normal ovarian follicular and oocyte development requires a series of temporally and spatially orchestrated events; however, several of the cellular pathways required for ovarian function are also used during the innate immune response to bacterial pathogens. We propose that activation of cellular pathways during this immune response has a negative impact on ovarian physiology, which is manifest as infertility detected after the clearance of the bacteria. This review highlights how new insights into infection and immunity in cattle are linked to infertility. © 2015 American Society of Animal Science. All rights reserved.
... Intrafollicular PON1 activity was also reduced by LPS injection. These results indicate that even short-term inflammatory response can affect the expression of key enzymes for steroidogenesis in the follicle and may affect the final follicular development and ovulation rate if this insult persists for longer periods as suggested before by others [25]. ...
Article
The aim of this study was to evaluate the effect of an acute systemic inflammatory response induced by lipopolysaccharide (LPS) in the serum and follicular fluid (FF) high-density lipoprotein (HDL) components, hormone concentrations and granulosa cell gene expression. For this purpose, twenty non-lactating Jersey dairy cows were submitted to a progesterone (P4) – estradiol (E2) based synchronization protocol. Cows received a single i.v. dose of LPS (2.5 μg/kg of body weight) or saline solution (CTL Group) 2 h after P4 insert removal. Blood, granulosa cells and FF samples were collected six hours after LPS injection. Five hours after LPS injection rectal temperature was increased in LPS (P < 0.0001, 40.4 ± 0.1 °C) compared to the CTL cows (38.8 ± 0.1 °C). Serum PON1 activity was reduced by LPS injection (130.2 ± 5.1 vs. 99.6 ± 3.3 U/mL; P < 0.001), as well as HDL-cholesterol concentrations (70.3 ± 5.3 vs. 50.1 ± 6.2 mg/dL; P < 0.05). The FF E2 and P4 concentrations were not different between groups (P > 0.05). The PON1 activity in the FF was also decreased by LPS injection (P = 0.01). In comparison to CTL group, cows injected with LPS had a ten fold reduction in STAR, TLR4 and TNF mRNA expression (P < 0.05). In conclusion, an intravenous LPS challenge in cows induced an acute systemic inflammatory response reducing HDL and its components in serum but not in the FF. Only PON1 activity serum reduction was reflected in the FF in the short term. Additionally, steroidogenic and inflammatory genes had reduced expression in the granulosa cells.
... Comin et al. (2013) reported greater concentrations of cortisol in hair from clinically compromised (e.g., laminitis, metritis, or mastitis) cows compared with those with an absence of disease. Additionally, Lavon et al. (2008) observed that animals administered Escherichia coli endotoxin showed an increase in cortisol in plasma, suggesting that an inflammatory response induces increases in cortisol. Some researchers have reported that an inflammatory infection caused by E. coli endotoxins administered into the uterine lumen has negative effects on reproduction, which suggests this may be due to the release of cortisol as a result of the inflammation (Lopez-Diaz and Bosu, 1992;Huszenicza et al., 2004). ...
Article
Full-text available
Hair cortisol has been used to measure chronic stress in dairy cows as it offers the advantage of being noninvasive, fast, and able to indicate levels of cortisol over long periods. The aim of this study was to determine the associations between hair cortisol with clinical disorders, reproductive status, and the development of subclinical endometritis in dairy cows. Furthermore, we aimed to determine the association between hair cortisol concentrations and blood markers associated with metabolic status and acute inflammation. In experiment 1, cows (n = 64) were hair sampled every 3 wk from the tail switch beginning at calving (d 0) until d 126 for cortisol analysis; blood samples were collected every 3 wk from d 0 until 42 for β-hydroxybutyrate and glucose analysis. In experiment 2, cows (n = 54) were chosen retrospectively by diagnosis of subclinical endometritis (END), subclinical endometritis and at least 1 clinical disease (END+CLIN), or as healthy (control) using a cytobrush and ultrasonography at 30 ± 3 d in milk. At the same time, animals were hair sampled for cortisol analysis and blood sampled for haptoglobin and ceruloplasmin analysis. Health records were recorded throughout both experimental periods. Animals with clinical disease presented higher cortisol concentrations than clinically healthy animals in experiment 1 [geometric mean (95% confidence interval); 8.8 (7.8, 9.9) vs. 10.7 (9.6, 12.0) pg/mg]; however, animals diagnosed with subclinical endometritis in experiment 2 did not differ in hair cortisol concentrations [11.7 (9.8, 14.0), 12.2 (9.3, 15.9), 10.5 (8.1, 13.6) pg/mg for control, END, and END+CLIN, respectively]. In experiment 1, an effect of sample day was noted, where d 21 had higher cortisol concentrations than d 42, 84, and 126, but not from d 0 for both parities. Within both experiments, a parity effect was present where multiparous animals consistently had higher cortisol concentrations than primiparous animals. Multiparous cows that became pregnant by 100 d postpartum had lower concentrations of hair cortisol at d 42 and 84 in milk. Lastly, other biomarkers associated with metabolic status and acute inflammation, such as glucose, β-hydroxybutyrate, haptoglobin, and ceruloplasmin, were not strongly correlated with measurements of cortisol in hair. Overall, hair cortisol measurements appear to be associated with clinical disorders and have a direct association with pregnancy status; however, concentrations of hair cortisol may not be suited to differentiate situations of stress with lower magnitudes, such as the development of subclinical disease. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
... However, experimental uterine LPS exposure (Peter et al., 1989;Karsch et al., 2002). Furthermore, ovulation is delayed in cows following systemic or intramammary administration of LPS, although GnRH has been used therapeutically to induce normal ovarian cyclicity in these animals (Suzuki et al., 2001;Lavon et al., 2008). The specific mechanisms by which LPS exposure at a distant site affects hypothalamic-pituitary function have yet to be elucidated; experimental models of systemic LPS administration (described previously) indicate the possibility of LPS entering the circulation and traveling to the brain, although it is interesting that blockade of TLR4 signaling seems to prevent LPS-induced GnRH-LH signal disruption (Haziak et al., 2014). ...
Article
Full-text available
Uterine contamination with bacteria is ubiquitous in the postpartum dairy cow. Nearly one-half of all postpartum dairy cows develop clinical disease resulting in metritis and endometritis, which cause depressed milk production and infertility. The causative links between uterine infection and infertility include a hostile uterine environment, disrupted endocrine signaling, and perturbations in ovarian function and oocyte development. In this review we consider the various mechanisms linking uterine infection with infertility in the dairy cow, specifically 1) innate immune signaling in the endometrium, 2) alteration in endocrine signaling in response to infectious agents, and 3) impacts of infection on ovarian function, oocyte development, and follicular development. Normal ovarian follicular and oocyte development requires a series of temporally and spatially orchestrated events; however, several of the cellular pathways required for ovarian function are also used during the innate immune response to bacterial pathogens. We propose that activation of cellular pathways during this immune response has a negative impact on ovarian physiology, which is manifest as infertility detected after the clearance of the bacteria. This review highlights how new insights into infection and immunity in cattle are linked to infertility.
... This includes both clinical and subclinical forms of intramammary infection (IMI) and involves both Gram-negative (G-) and Gram-positive (Gþ) bacteria (Barker et al. 1998;Schrick et al. 2001;Santos et al. 2004;Hertl et al. 2010). Experimental models to study ovarian responses are based primarily on mammary inoculation with Escherichia coli or its endotoxin (lipopolysaccharide (LPS)) and are mostly used to examine the immediate acute disruptive effects on follicular function (Lavon et al. 2008(Lavon et al. , 2011aWilliams et al. 2008). Less is known about the long-term chronic effects of mastitis on ovarian function. ...
Article
Subclinical chronic mastitis was induced to examine the effects on oocyte developmental competence. Uninfected Holstein cows were intramammary administrated with serial (every 48h for 20 days) low doses of toxin of Staphylococcus aureus origin (Gram-positive; G+), endotoxin of Escherichia coli origin (Gram-negative; G-) or sterile saline (control). Follicular fluid of toxin- and saline-treated cows was aspirated from preovulatory follicles and used as maturation medium. Oocytes harvested from ovaries collected at the abattoir were matured and then fertilised and cultured for 8 days. The percentage of oocytes undergoing nuclear maturation, determined by meiotic nuclear stages, did not differ between groups. Cytoplasmic maturation, determined by cortical granule distribution, was affected by both toxins (PPPPTGS2) mRNA increased, whereas that of growth differentiation factor 9 (GDF9) decreased in matured oocytes. In addition, PTGS2 expression increased and POU class 5 homeobox 1 (POU5F1) expression decreased in 4-cell embryos developed from both G+ and G- oocytes. Thus, regardless of toxin type, subclinical mastitis disrupts oocyte cytoplasmic maturation and alters gene expression in association with reduced developmental competence.
... The preovulatory follicles are found for increasing circulating E2 levels at estrus, and was positively correlated with preovulatory follicles diameters Rahman et al., 2012a, b). Therefore, occurring the mastitis pre-AI (during the follicular phase) reduced the pulsatile secretion of LH, leading to low E2 secretion close to estrus, and delayed surge of LH and consequently occurring the ovulation (Hockett et al., 2005;Lavon et al., 2008). ...
Article
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Abstract | This study aimed to determine the influence of early postpartum clinical mastitis on the reproductive performance, antioxidant, hormonal profile and trace elements in Egyptian buffaloes. A total of 90 multiparous lactating Egyptian buffaloes (500-600 kg live body weight, 5-7 years old, 3-5 parities, and 10.75 ± 2.66 kg/day milk yield were used in this study. The buffaloes were managed and feed at similar traditional conditions. Mastitis diagnosis was performed 21 days after calving, then animals (n=90) were grouped to normal (n= 75), and clinical mastitis (n=15) groups. Results show that interval from calving to first estrus (31.60±0.86 vs. 33.10±0.98 d) or first service (55.20±0.97 vs. 61.00±1.96) was not affected (P≥0.05). Mastitis decreased (P<0.05) estrus/mating (93.3 vs. 80.0%) and pregnancy rates (86.66 vs. 53.33%), prolonged (P<0.001) days open (63.45±3.25 vs. 104.10±3.92 d), and increased services number required for conception (1.35±0.11 vs. 2.800±0.25 services). Mastitis decreased (P<0.0001) reduced glutathione (5.66±0.182 vs. 4.71±0.302 mmol/l) and total antioxidant capacity (1.64±0.046 vs. 0.76±0.049 mmol/l), and increased (P<0.0001) in malondialdehyde (0.80±0.043 vs. 1.68±0.064 mmol/ml). Mastitis significantly decreased serum concentration of progesterone (P4), estrogen (E2), thyroxin (T4), zinc (Zn), and selenium (Se) by about 24.05, 13.80, 5.36, 2.50, and 3.44%, respectively, while triiodothyronine (T3) concentration showed non-significant decrease by about 3.77%. Mastitis incidence at early postpartum in lactating Egyptian buffaloes delayed the resumption of estrous and ovarian activity and decreased pregnancy rate, antioxidant status, thyroid and reproductive hormones and trace elements such as Zn and Se. Keywords | Mastitis, Buffaloes, Pregnancy rate, Antioxidant, Trace elements.
... Reproductive and nonreproductive diseases promote immune and inflammatory responses that may compromise ovulation (Suzuki et al., 2001;Lavon et al., 2008), fertilization (Ribeiro et al., 2016), embryonic development and survival (Soto et al., 2003;Hansen et al., 2004), hypothalamic-pituitary-gonadal axis functionality (Herman et al., 2010), ovarian follicular growth and steroidogenesis (Herath et al., 2007), oocyte competence (Roth et al., 2013), and uterine environment for pregnancy maintenance (Bromfield et al., 2015). The modifications in the endometrium environment in the preimplantation period have been described (Forde et al., 2011). ...
Article
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The objective of the current study was to evaluate the effects of 2 intramammary infusions of lipopolysaccharide (LPS) on inflammatory and reproductive parameters and endometrial gene expression of lactating Holstein cows. At 35 ± 7 d in milk, 20 cows were submitted to a Double Ovsynch program and randomly assigned to control (n = 11) and LPS (n = 9) treatments. Cows from the LPS treatment received 2 intramammary infusions of 25 µg of LPS after morning milking on d 5 and 10 post-AI, whereas control cows were infused with only saline. Blood samples were taken and ultrasound scanning of the ovaries was performed during the entire study before and after AI to determine haptoglobin, tumor necrosis factor-α, and progesterone concentrations as well as response to the hormonal protocol and corpus luteum diameter. Milk yield was evaluated and samples were taken for somatic cell count at 0, 10, 24, 34, and 96 h relative to each infusion. Rumen-reticular temperature was recorded using a rumen-reticular bolus logger and summarized hourly. On d 15 post-AI, uterine flushing for conceptus recovery and endometrial biopsies were performed. Samples of endometrium from cows with positive embryo recovery (control = 5; LPS = 6) were submitted to mRNA extraction and quantitative reverse-transcription PCR analysis of 96 target genes. Haptoglobin concentrations in plasma were greater for LPS treatment (control = 0.24 ± 0.07, LPS = 0.89 ± 0.06 optical density), but tumor necrosis factor-α concentrations were similar (control = 0.67 ± 0.11, LPS = 0.46 ± 0.11 ng/mL) between treatments. Lipopolysaccharide reduced milk yield after treatment (control = 34.3 ± 1.5, LPS = 29.4 ± 1.6 kg/d), whereas somatic cell count (log) was greater in LPS-treated cows until 34 h after infusions (control = 2.3 ± 0.1, LPS = 3.3 ± 0.1 cells/mL of milk). Rumen-reticular temperature of LPS cows was elevated between 5 and 10 h after each infusion compared with control cows (control = 39.5 ± 0.1, LPS = 40.1 ± 0.1°C). Progesterone concentration after AI was unaffected by treatment or pregnancy status as well as corpus luteum diameter and conceptus length on d 15. Lipopolysaccharide treatment altered the expression of 13 key genes in the endometrium (mostly upregulated), whereas another 17 tended to be modulated. Modified gene expression included genes related to immune response (PTX3 = 2.34-fold increase; IL6 = 3.42-fold increase; and TCN1 = 2.52-fold increase), adhesion molecules (CADM3 = 1.93-fold increase; MMP19 = 1.49-fold increase; EMMPRIN = 1.20-fold increase; SELL = 1.91-fold increase), Wnt signaling pathway (WNT2, FZD4, and FZD7, all <1.5-fold increase), and interferon-stimulated genes (BMP15 = 0.27-fold decrease; ISG15 = 2.17-fold increase, and MX2 = 2.23-fold increase). In summary, intramammary infusions of LPS were able to trigger an inflammatory response with no effect on corpus luteum diameter and concentration of progesterone in plasma. However, a limited but important set of modulations in the endometrium gene expression at d 15 of gestation was found.
... However, experimental uterine LPS exposure (Peter et al., 1989;Karsch et al., 2002). Furthermore, ovulation is delayed in cows following systemic or intramammary administration of LPS, although GnRH has been used therapeutically to induce normal ovarian cyclicity in these animals (Suzuki et al., 2001;Lavon et al., 2008). The specific mechanisms by which LPS exposure at a distant site affects hypothalamic-pituitary function have yet to be elucidated; experimental models of systemic LPS administration (described previously) indicate the possibility of LPS entering the circulation and traveling to the brain, although it is interesting that blockade of TLR4 signaling seems to prevent LPS-induced GnRH-LH signal disruption (Haziak et al., 2014). ...
Conference Paper
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Abstract Text: One of the most common endemic diseases of dairy cattle is bacterial infection of the uterus after parturition. These infections damage the endometrium lining the uterus, reduce the production of milk, and cause infertility. Uterine disease is caused by Escherichia coli, Trueperella pyogenes, anaerobic bacteria and viruses. These microbes posses a range of virulence factors that caused inflammation and damage in the endometrium. Innate immunity is an ancient system of defence against microbes, dependent on host cellular pattern recognition receptors such as Toll-like Receptors, which bind pathogen-associated molecular patterns. Epithelial and stromal cells are the first line of defence against microbes in the endometrium, and they express most Toll-like Receptors. Activation of Toll-like Receptor signalling leads to the secretion of chemokines, cytokines and prostaglandins, which attract and activate neutrophils and macrophages to clear the microbes. Microbial factors and host intracellular pathways regulate the scaling of the innate immune response, and the severity of postpartum uterine disease. Uterine disease also compromises ovarian function, with impacts on the corpus luteum, and on ovarian follicle development from primordial to antral follicles. Whilst healthy ovarian follicles are devoid of immune cells, granulosa cells express Toll-like Receptors and have roles in innate immunity. Pathogen-associated molecular patterns perturb granulosa cell endocrine function, stimulate the secretion of inflammatory mediators from granulosa cells, and lead to damage of oocytes. In conclusion, the fundamental mechanisms of innate immunity and inflammation in the female genital tract of dairy cattle are important for animal health and fertility. Work in the Sheldon laboratory is funded by the Biotechnology and Biological Sciences Research Council (BBSRC) in the UK. Keywords: dairy cattle, uterus, parturition
... Toujours à l'échelle centrale, les cytokines aff ectent le système hypothalamo-hypophysaire. En premier lieu, la sécrétion de LH est réduite, le pic préovulatoire de LH est supprimé ou a minima, plus tardif et de plus faible ampleur, responsable de suboestrus (Hockett et al 2005) et d'anovulation (Suzuki et al, 2001 ;Lavon et al, 2008Lavon et al, , 2010. Cet eff et direct sur la LH est renforcé par une augmentation de la cortisolémie. ...
... The preovulatory follicles are found for increasing circulating E2 levels at estrus, and was positively correlated with preovulatory follicles diameters Rahman et al., 2012a, b). Therefore, occurring the mastitis pre-AI (during the follicular phase) reduced the pulsatile secretion of LH, leading to low E2 secretion close to estrus, and delayed surge of LH and consequently occurring the ovulation (Hockett et al., 2005;Lavon et al., 2008). ...
Article
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This study aimed to determine the influence of early postpartum clinical mastitis on the reproductive performance, antioxidant, hormonal profile and trace elements in Egyptian buffaloes. A total of 90 multiparous lactating Egyptian buffaloes (500-600 kg live body weight, 5-7 years old, 3-5 parities, and 10.75 ± 2.66 kg/day milk yield were used in this study. The buffaloes were managed and feed at similar traditional conditions. Mastitis diagnosis was performed 21 days after calving, then animals (n=90) were grouped to normal (n= 75), and clinical mastitis (n=15) groups. Results show that interval from calving to first estrus (31.60±0.86 vs. 33.10±0.98 d) or first service (55.20±0.97 vs. 61.00±1.96) was not affected (P≥0.05). Mastitis decreased (P<0.05) estrus/mating (93.3 vs. 80.0%) and pregnancy rates (86.66 vs. 53.33%), prolonged (P<0.001) days open (63.45±3.25 vs. 104.10±3.92 d), and increased services number required for conception (1.35±0.11 vs. 2.800±0.25 services). Mastitis decreased (P<0.0001) reduced glutathione (5.66±0.182 vs. 4.71±0.302 mmol/l) and total antioxidant capacity (1.64±0.046 vs. 0.76±0.049 mmol/l), and increased (P<0.0001) in malondialdehyde (0.80±0.043 vs. 1.68±0.064 mmol/ml). Mastitis significantly decreased serum concentration of progesterone (P4), estrogen (E2), thyroxin (T4), zinc (Zn), and selenium (Se) by about 24.05, 13.80, 5.36, 2.50, and 3.44%, respectively, while triiodothyronine (T3) concentration showed non-significant decrease by about 3.77%. Mastitis incidence at early postpartum in lactating Egyptian buffaloes delayed the resumption of estrous and ovarian activity and decreased pregnancy rate, antioxidant status, thyroid and reproductive hormones and trace elements such as Zn and Se.
... Inflammatory diseases, such as endometritis and mastitis, play a pivotal role in dairy cows and reduce their reproductive performance [1,2]. To investigate the effects of inflammation on cows' fertility, treatment with lipopolysaccharide (LPS), the endotoxin from the outer membrane of gramnegative bacteria, was used as a model [3][4][5]. In this model, different routes of administration of LPS were investigated, namely intravenous [6], intrauterine [7], and intramammary [8]. ...
Article
Recently, we observed that lipopolysaccharide (LPS) suppresses corpus luteum (CL) function in isolated perfused ovaries. It remained unclear if this suppression was due to increased luteal PGF2α secretion or LPS-induced apoptosis. Therefore, possible impacts of PGF2α and LPS were inhibited by a non-steroidal anti-inflammatory drug (flunixin) and an endotoxin-binding agent (polymyxin B), respectively. Bovine ovaries with a mid-cycle CL were collected immediately after slaughter and perfused for 240 min. After 50 min of equilibration, either flunixin or polymyxin B (5 μg/ml of each) were added to the perfusion medium of six ovaries, respectively. All ovaries (n = 12) were treated with E.coli LPS (0.5 μg/ml) 60 min after the onset of perfusion, and received 500 I.U. of hCG after 210 min of perfusion. Progesterone and PGF2α were measured in the effluent perfusate every 10 and 30 min, respectively. Biopsies of the CL were collected every 60 min to determine the mRNA expression of the cytokine TNFA and factors of apoptosis (CASP3, -8). Flunixin-treatment inhibited the increase of PGF2α after LPS-challenge that was observed in the polymyxin B-treated (PX-LPS) ovaries. After hCG-stimulation, progesterone secretion increased (P< 0.05) in group PX-LPS but not in the flunixin-treated (F-LPS) ovaries. Compared to initial values before LPS-challenge, luteal mRNA expression of TNFA and CASP3 was increased (P< 0.05) in group F-LPS at 120 and 180 min, respectively, and those of CASP8 was decreased (P< 0.05) in PX-LPS at 60 and 120 min after LPS-treatment. In conclusion, although flunixin managed to inhibit PGF2α, it did not suffice to successfully prevent LPS-induced apoptosis. However, endotoxin-binding polymyxin B resulted in luteal responsiveness to hCG after LPS-challenge.
... Significant difference between groups with the same tags (p<0.05) cles in the follicular wave (Wiltbank et al. 2000, Lavon et al. 2008). This explains our results, as M group cows had more double ovulation at the time of first ovulation compared to H group cows, but the difference was not significant. ...
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The aim of this study was to determine how puerperal metritis influences the resumption of estrous cycle in dairy cows. The ovaries of 72 multiparous Holstein cows (38 healthy and 34 metritic-after treatment) were ultrasonographically scanned until the first ovulation post-partum and 7 days after to confirm the ovulation. All 72 cows were divided in to 4 groups: HSO (healthy with single ovulation) (n=29), MSO (metritic with single ovulation) (n=21), HDO (healthy with double ovulation) (n=9), and MDO (metritic with double ovulation) (n=13). The proportion of cows that had DO in the first ovulation postpartum was similar between M and H groups, 38.2% and 23.6%, respectively (p>0.05). There was a difference between HDO and MDO groups comparing the first dominant follicle ovulation postpartum (11.4±2.7 and 20±1 days, respectively p<0.05) and the diameter of the ovulatory follicles (15.3±1.9 mm and 17.3±1.7 mm, respectively p<0.05). The percentage of cows that had double follicle dominance in the first follicular wave after first ovulation was higher in the M groups (33.3% (MSO) vs. 6.9% (HSO) (p<0.05) and (69.2% (MDO) vs. 22.2% (HDO) (p<0.05)). The MSO group dominant follicle diameter was bigger for cows which had one dominant follicle (p<0.05). It might be concluded that dairy cows after puerperal metritis need more time until the first ovu-lation. Also, metritic cows have a higher risk for double dominance in the first follicular wave, after the first ovulation.
... This might explain the altered ability of cows to respond to the hormonal treatments and synchronize ovulation, which eventually affected the rate of pregnancy. In particular, the synchronization protocol used estradiol to induce ovu- lation, and pathogen-associated molecular patterns can disrupt the spontaneous LH surge in dairy cows (Lavon et al., 2008). ...
Article
The objectives of the present prospective cohort study were to identify risk factors for inflammatory diseases in Holstein-Gyr crossbred dairy cows and characterize the associations of those diseases with pregnancy per embryo transfer (ET). Diseases were diagnosed in the first 60 d postpartum in 252 primiparous and 481 multiparous cows. Uterine diseases (UTD) included retained placenta, metritis, clinical endometritis, and subclinical endometritis. Nonuterine diseases (NUTD) included mastitis, lameness, pneumonia, and displaced abomasum. Blood was sampled on d 0, 1, and 2 postpartum and analyzed for concentrations of haptoglobin, fatty acids, total Ca (tCa), P, and Mg, and again on d 8 postpartum and analyzed for concentration of β-hydroxybutyrate. The association between concentrations of metabolites in serum and inflammatory diseases was determined. Cows received a timed ET program starting 28 ± 3 d postpartum with first ET at 46 ± 3 d postpartum using fresh in vitro-produced embryos. Pregnancy was diagnosed on d 31 and 59 of presumptive gestation. Overall, 63.3% of the cows were diagnosed with UTD and 20.6% with NUTD. The risk factors for UTD included season of calving, parity group, calving problems, days with subclinical hypocalcemia, and serum concentrations of haptoglobin and Mg, whereas the risk factors for NUTD were parity group and serum Mg concentration. Cows that developed UTD had increased concentrations of haptoglobin on d 2 and fatty acids on d 1 and 2, and reduced concentrations of tCa on d 1 and 2 and of P and Mg on d 2 postpartum compared with cows without UTD. Cows that developed NUTD had increased concentrations of fatty acids on d 0 to 2 postpartum, and decreased concentrations of tCa and P on d 0 and 1, and of Mg on d 1 and 2 postpartum compared with cows without NUTD. Cows that developed NUTD had a 340-kg reduction in milk yield in the first 60 d postpartum. Inflammatory diseases were associated with lesser body condition score and increased loss of body condition in the first 70 d postpartum. Maintenance of pregnancy after ET was reduced in UTD cows following the first (41.7 vs. 25.4%) or all ET (46.4 vs. 36.2%), whereas maintenance of pregnancy was reduced in NUTD cows only at the second ET (39.0 vs 25.9%). The reduced pregnancy maintenance in UTD cows combined with a reduced 21-d service rate (61.9 vs. 54.8%) decreased the 21-d cycle pregnancy rate (28.6 vs. 19.9%) and the hazard of pregnancy to 300 d postpartum by 35%, resulting in an extra 32 d open. In conclusion, inflammatory diseases depressed fertility in dairy cows receiving ET, with the greatest impact observed in UTD cows. This suggests that local inflammation of the uterus impairs maintenance of pregnancy in dairy cows following ET.
... Pathogenic bacteria which are associated with this disease condition are Escherichia coli, Trueperella pyogenes, Fusobacterium necrophorum, Prevotella and Bacteroides [15][16][17][18]. They produce bacterial endotoxins which are known to elicit negative impact on reproduction as they may affect estradiol and progesterone secretion and alter follicular growth and the normal development of the corpus luteum; causing ovulation failure by interfering with LH production; prolong the life span of corpus luteum by increase PGE2 secretion and induce embryo mortality [18][19][20][21][22]. Polymorphonuclear granulocytes represent the first and principal immunologic defense mechanism in the uterus [23][24][25]. ...
Article
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Introduction Cytological endometritis or subclinical endometritis (SCE) is single most vital reproductive impairments in dairy animals studied in the past decade. It can be defined as the superficial inflammation of the endometrium (no deeper than the stratum spongiosum) without noticeable clinical signs, but remarkably affecting reproductive performances [1-3]. The absence of pus in the postpartum genital tract does not mean that the tract is normal. The importance of subclinical endometritis has emerged over the last 15 years, with the realisation that cytological evidence of inflammation of the endometrium is associated with reduced fertility. Trans-rectal palpation of the uterus is the most common method of diagnosing postpartum uterine diseases; however, it is very difficult to find out SCE by this method [4,5]. Cytology is considered the best technique to diagnose SCE due to its feasibility and fair reliability. Different techniques have been described to obtain endometrial samples for cytological examination in both mares and cows, such as cotton swab, uterine biopsy, low volume uterine lavage (LVF), or Cyto brush (CB) [6,7]. Out of different methods of collection of uterine samples, CB is the most reliable method for diagnosing bovine cytological endometritis [8]. In 2004, for the first time, the CB was used to obtain endometrial samples in cows [9]. Prevalence and detrimental effects of subclinical endometritis SCE is the inflammation of the uterine endometrium without mucopurulent material accumulation in the vagina and any systemic symptom [10]. Its prevalence varied between 20-53 % from 20-60 days postpartum. The incidence of SCE in cattle and buffaloes was found 15 % and 26 %, respectively. Postpartum uterus is very prone to get several types of microbial contamination that can cause severe economic losses to farmers in the form of an increasing in the number of services per pregnancy, increasing the length of calving-conception interval, abortions, infertility and death. Etiopathogenesis SCE is the inflammation of the endometrium without clinical signs and evidence of infection [11,12]. In early postpartum period, uterine pathogens may compromise the reproduction both by causing direct endometrial damage and by producing toxins [13,14]. Pathogenic bacteria which are associated with this disease condition are Escherichia coli, Trueperella pyogenes, Fusobacterium necrophorum, Prevotella and Bacteroides [15-18]. They produce bacterial endotoxins which are known to elicit negative impact on reproduction as they may affect estradiol and progesterone secretion and alter follicular growth and the normal development of the corpus luteum; causing ovulation failure by interfering with LH production; prolong the life span of corpus luteum by increase PGE2 secretion and induce embryo mortality [18-22]. Polymorphonuclear granulocytes represent the first and principal immunologic defense mechanism in the uterus [23-25]. An elevated number of polymorphonuclear neutrophils (PMNs) in the uterine lumen indicate an inflammatory reaction of the endometrium. The suggested threshold value for polymorphonuclear cells (PMN) as diagnostic for subclinical endometritis depends on the time postpartum and varies from 5 to 18% [26]. It has also been publicized that an overall threshold of 5% PMN is entitled for all cows and buffaloes between 21 and 62 days postpartum. Kasimanickam et al. (2004) found >18 percent neutrophils at 20-33 days postpartum or >10 percent neutrophils at 34-47 days postpartum in uterine samples as an indicative of subclinical endometritis whereas, Gilbert et al. (2005) found 5 percent neutrophils at 40 to 60 days postpartum as an indicator of sub-clinical endometritis, while Barlund et al. (2008) used a neutrophil threshold value of 8 percent at 28-41 days postpartum in cattle to declare endometritis. Various research workers have used different threshold values of PMN cells for the identification of sub-clinical endometritis. Abstract: In the last decade, several new concepts in the field of diagnosis of cytological or subclinical endometritis came into light. This review summarizes the recent discussion about diagnosis and etiopathogenesis of subclinical endometritis. Subclinical endometritis is recognized by findings of endometrial cytology, which is usually done with the cytobrush-technique or by low-volume flushing of the uterus. The sampling procedure is negligibly invasive and has no adverse effect on successive conception rate. The impact of subclinical endometritis on reproductive performance is categorized by reduced conception rates, and prolonged days to first service and days open. In addition, it has been well established that subclinical endometritis has an effect on survival and quality of the embryo. Out of different methods of collection of uterine samples, cytobrush is the most reliable method for diagnosing bovine cytological endometritis. Different methods of cytological sample collection Cytology is considered the best technique to diagnose SCE due to its feasibility and fair reliability. Different techniques have been described to obtain endometrial samples for cytological examination in both mares and cows, such as cotton swab, uterine biopsy, low volume uterine lavage (LVF), or Cyto brush (CB). Out of different methods of collection of uterine samples, CB and LVF are found less invasive. Further, the CB method is less harmful than LVF because the fluid (normal saline, 0.9%) used in LVF produces endometrial irritation. Moreover, the saline solution extends the time required to obtain samples (a 17% failure to obtain saline) and increases the alteration of cells harvested via LVF [26]. So, CB as the most reliable method for diagnosing bovine cytological endometritis. Animals with subclinical endometritis do not show any clinical sign of endometritis. Endometrial cytology is the most used technique to diagnose SCE both in field and research [27]. The measurement of the proportion of PMNs in cytology slides is the hallmark for SCE diagnosis. Cytological sample collection by cytobrush and slide staining Cytobrush assembly consists of stainless-steel rod and cytobrush, which is guarded by a stainless-steel sheath. This assembly needs to be introduced into the uterine body through the vagina and cervix. Then, stainless-steel sheath is retracted to expose the cytobrush and rotated twice in a clockwise direction to obtain cells from the endometrium. After removing the cytobrush assembly from the vagina, the cytobrush containing cellular material is rolled onto a glass slide and air dried. The slides should be stained using Giemsa stain followed by examination under a microscope (400× magnification). The numbers of epithelial endometrial cells and PMNs are counted (up to 200 cells per slide) and the percentage of PMNs present thus calculated [28-30]. Future prospect Cytobrush technique is simple, non-invasive, consistent and efficient diagnostic aid which provides adequate uterine cells to accomplish both cytology and gene expression analysis in single sample. Research studies have supported that endometrial cytology by cytobrush technique is most efficient and early diagnostic technique which can be used along with microbial assay for detecting existence and severity of endometritis. Also, antimicrobial sensitivity analysis of cytological sample helps in accurate selection of antibiotic thereby minimising both cost of therapy and antimicrobial resistance. Thus, cytobrush technique is advantageous in diagnosis as well as treatment of subclinical endometritis in bovines. Application of review: Article will provide information on cytobrush technique for diagnosing subclinical endometritis.
... If inflammation precedes AI, its effects may compromise follicular growth, steroidogenesis (Herath et al. 2007), and oocyte competence (Roth et al. 2013). When inflammation occurs after AI, reproductive processes, such as ovulation (Lavon et al. 2008) and fertilization , as well as the establishment of pregnancy and first steps of embryonic development can be compromised (Soto et al. 2003). In addition, Campos et al. (2018) showed that induced mastitis with LPS from Escherichia coli was able to trigger an inflammatory response, similar to naturally occurring CM, and also caused important changes in the endometrium gene expression during the first 15 days of gestation. ...
Article
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The objective of this study was to evaluate the effects of clinical mastitis (CM) occurring before or after the first AI postpartum, and puerperal diseases (PD) on the pregnancy per artificial insemination (P/AI), number of AI/conception, and days open (DO) of two different dairy herds (Girolando and Holstein). The CM, PD (retained placenta and metritis), and reproductive data were collected from two dairy farms throughout 1 year. Both farms were located in the southern region of Minas Gerais State, Brazil. One herd was composed of Girolando cows and the other of Holstein cows. Cows were inseminated after estrus detection or submitted to timed AI. Only CM cases (clots in milk accompanied or not by udder inflammation) that occurred before or after first AI postpartum (from calving until 35 days after the first AI) were considered. There were no effects of CM, PD, or both diseases on the reproductive efficiency of the Girolando herd. In the Holstein herd, a reduce P/AI and prolonged DO were verified for those affected by ≥ 2 CM cases. Holstein cows with CM also required more inseminations to become pregnant. A decrease in the P/AI and an increase in the number of AI/conception and DO were observed in cows of the Holstein herd that developed only CM, only PD, and for those diagnosed with both diseases. In summary, considering that some management differences exist between the two dairy farms, CM occurrence (before or after the first AI postpartum) and puerperal diseases negatively affected the reproductive efficiency of the Holstein herd. However, these diseases did not compromise the reproductive efficiency of the Girolando herd.
... Bacterial endotoxins affect reproductive activity in diverse manners (Williams et al. 2007). Thus, these bacterial products disrupt follicular growth, alter progesterone and follicle estradiol secretion, modify the pattern of LH secretion and delay ovulation (Suzuki et al. 2001;Williams et al. 2008;Lavon et al. 2008Lavon et al. , 2011 and also cause embryonic death (Soto et al. 2003a, b). Probably, one or more of these mechanisms causing infertility were responsible for the nontreated cows needed more inseminations to become pregnant and had longer intervals for conception. ...
Article
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New postpartum strategies have been developed in dairy cows to ameliorate uterine health and reproductive performance, especially the first service conception rates. This study aimed to assess the effect of intrauterine therapy with ozone (IUTO) in early postpartum on subclinical endometritis prevalence and reproductive parameters in dairy cows under commercial farm conditions. For this purpose, eighty clinically healthy cows with a body condition score between 3.0 and 3.5, from four dairy farms, were randomly allocated into two groups: ozone therapy group (OG, n = 40), which were subjected to IUTO, and control group (CG, n = 40). Content of uterine polymorphonuclear (PMN) leukocytes and subclinical endometritis (SE) percentage were assessed at 35 days after calving by uterine cytology. A second cytology was performed 72 h after IUTO. Reproductive parameters such as interval calving to first service (IFS), number of services per conception (nSC), interval calving to conception (ICC) and first service conception rate (FSCR) were analysed. The second endometrial cytology demonstrated that IUTO reduced (P < 0.01) both PMN (3.7 ± 1.4 vs. 7.6 ± 1.1%) and SE (5.0 vs. 50.0%) percentages compared with CG. Likewise, after ozone treatment, both nSC (2.1 ± 0.3 vs. 3.1 ± 0.2; P < 0.01) and ICC (126.2 ± 9.7 vs. 149.0 ± 9.0; P = 0.0672) decreased, and FSCR increased (50.0 vs. 16.2%; P < 0.01) compared with CG. In conclusion, intrauterine ozone therapy applied at 35 days after calving reduced subclinical endometritis prevalence and improved reproductive performance in postpartum dairy cows managed in a pasture-based system.
... The effect of CM on reproductive performance is an issue that has interested researchers since the early 2000s. Studies have revealed that CM affects reproductive performance in the following ways: prolonged CFSI (longer than 22 days) and CCI (longer than 44 days) [11], increased number of services per conception [11], difficulty of estrus determination, ovulation delay [12,13], shortening of the interestrus interval [14], deterioration in oocyte development [15], decrease in the conception rate [16,17], and increased risk of abortion [18]. ...
Article
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The objective was to evaluate the effects of clinical mastitis (CM) on reproductive performance in high-milk–producing cows before the service period. The data of Holstein Friesian cows (n = 550) in a commercial farm was retrospectively evaluated. The diagnosis of CM was made by the presence of visible abnormalities in milk or symptoms of inflammation of one or more of the quarters. Cows were checked to detect CM prior to each milking. Calving to first service interval (CFSI), calving to conception interval (CCI), and services per conception (SC) were evaluated as reproductive parameters. Calving to first service interval (83.68 ± 3.18 vs. 74.57 ± 1.08; P < 0.05) and CCI (168.48 ± 8.59 vs. 132.86 ± 3.44; P < 0.001) were prolonged by 11.77% and 26.81%, respectively, and the number of SC (3.16 ± 0.21 vs. 2.42 ± 0.09; P < 0.001) was increased by 30.58% in cows experiencing CM. The culling candidate rate in nonpregnant cows was higher in the mastitis group (4.35%; 6/132) than in the healthy group (0.48%; 2/418). Calving season, time period of CM, and lactation number were not associated with the negative effects of mastitis in reproductive performance (P > 0.05). In conclusion, CM in early lactation has an adverse impact on reproductive performance in high-milk–producing dairy cows. The negative effects of CM on CFSI, CCI, and SC were not interrelated with calving season, the timing of CM, or parity.
... Thus, the infusion of saline per se had no influence on milk SCC. When only saline is infused into the mammary gland of a healthy cow (without LPS infusion in other quarters), milk SCC of the infused quarter is not altered (Lavon et al., 2008). However, intramammary LPS infusion in one-quarter reduces milk yield of non-LPS infused quarters of that cow. ...
Article
The objective of this study was to determine the effect of dietary supplemental Zn source and evaporative cooling on intake, milk yield and composition, and the rate of leukocyte migration into the mammary gland following intramammary lipopolysaccharide infusion. Multiparous Holstein cows (n=72) were assigned to one of 4 treatments with a 2×2 factorial arrangement including two sources of supplemental Zn: 75 mg/kg Zn hydroxychloride or 35 mg/kg Zn hydroxychloride + 40 mg/kg Zn-Met complex each with or without evaporative cooling. The cooling system was implemented by the use of fans and misters over the freestall and feeding areas. On d 34 of the experiment, cows (n = 16; days in milk = 263 ± 63 d) received an infusion of 10 μg of lipopolysaccharide, or a saline control, in the left or right rear quarters. Individual milk samples from both quarters were collected at -12, -4, 0, 6, 12, 24, 48, 72, 96, 120, 144, and 168 h relative to infusion and analyzed for composition and bovine serum albumin. Rectal temperature and respiration rate were assessed and blood samples were collected at the same time points (with an additional sample at 3 h) for analyses of lactose and cortisol. Complete blood counts were performed on samples collected within the first 24 h post infusion. Intramammary lipopolysaccharide infusion reduced (P < 0.01) milk yield, dry matter intake and feed efficiency regardless of dietary or cooling treatments. Non-cooled cows tended (P = 0.09) to have greater feed efficiency (=milk yield/dry matter intake) at 1 d after infusion than those subjected to cooling. Intramammary lipopolysaccharide infusion dramatically increased (P < 0.01) milk SCC but treatments had no apparent impact on milk SCC. Compared with cooled cows, non-cooled cows had greater (P < 0.05) plasma lactose concentrations, but lower (P < 0.03) blood concentrations of neutrophils and lymphocytes at 3 h post infusion. This suggests a greater leukocyte migration into the mammary gland of heat-stressed cows. In conclusion, non-cooled cows tended to maintain greater feed efficiency and appeared to have greater leukocyte migration into the mammary gland immediately after intramammary lipopolysaccharide infusion compared with cooled cows. Dietary supplemental Zn source had no impact on measures assessed after intramammary lipopolysaccharide infusion.
... The occurrence of health disorders before AI may result in late ovulation, anovulation, absence of estrous behavior, and extended intervals between calving and first AI (Suzuki et al., 2001;Lavon et al., 2008). In this context, some inflammatory mediators, such as the interleukins, tumor necrosis factor (TNF-α), nitric oxide, and PGF 2α could be considered limiting factors for embryonic development (Soto et al., 2003;Hansen et al., 2004). ...
Article
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This study aimed to evaluate the effect of repeated intravenous lipopolysaccharide (LPS) infusions in nonlactating heifers on (1) the systemic proinflammatory state as measured by biomarkers in blood and plasma, and (2) endometrial gene expression of candidate transcripts on d 15 of gestation. Our hypothesis was that target transcripts related to a major functional group would be negatively modified in the preimplantation endometrium by the LPS treatments. In the first experiment (n = 13), a systemic proinflammatory state [defined as increased plasma concentrations of tumor necrosis factor (TNF)-α and haptoglobin for 2 wk] was established using 2 different sequential LPS infusion protocols. In the second experiment, heifers (n = 22; 11 mo of age) had their time of ovulation synchronized by a modified Ovsynch protocol and were enrolled in 1 of 2 treatments: control (CON; n = 11), which received sterile saline solution i.v., and LPS treatment (LPS; n = 11), submitted to repeated i.v. LPS injections (0.10, 0.25, 0.50, 0.75, 1.00, and 1.25 µg/kg) starting 2 d after artificial insemination (AI; d 0) and then every other day until d 15 after AI. At each LPS injection, rectal temperatures were measured hourly for 6 h. Blood samples were collected from d −1 to d 13 for analyses of progesterone, TNF-α and haptoglobin in plasma, along with white blood cell (WBC) count and differential analysis. On d 15, endometrium tissue biopsies were taken and kept at −80°C until quantitative real-time PCR analysis of 30 target transcripts related to the immune system, adhesion molecules, and endometrium receptivity. Data were checked for normality and analyzed by repeated-measures ANOVA using PROC UNIVARIATE and PROC MIXED of SAS (SAS Institute Inc., Cary, NC). After each LPS injection, temperature was greater in the first 4 h in the LPS group compared with CON. Both TNF-α and haptoglobin increased in the LPS treatment with a significant treatment by day interaction. Total leukocyte count did not differ between treatments, but the differential count increased for neutrophils, band cells, and monocytes, and decreased for lymphocytes and eosinophils in LPS compared with CON. Progesterone concentrations in plasma did not differ between treatments during the experimental period. Out of 30 target genes analyzed, 3 transcripts were differentially expressed: indoleamine 2,3-dioxygenase (IDO; fold-change = 0.48) and pentraxin-3 (PTX3; fold-change = 0.38) were downregulated, whereas myxovirus-resistance protein (MX1; fold-change = 2.85) was upregulated in the LPS group. Sequential LPS injections were able to induce a prolonged systemic proinflammatory state, but effects on gene expression were limited to transcripts associated with the immune system. These results suggest that a mechanism for subfertility is linked to a proinflammatory state in dairy heifers.
... In postpartum cows, endotoxin in the uterus suppresses the luteinising hormone (LH) surge and prevents ovulation (Peter et al. 1989). In addition, during the follicular phase, endotoxin decreases LH pulse frequency, decreases oestradiol, and interrupts the LH surge and ovulation in cattle (Suzuki et al. 2001, Lavon et al. 2008). Similar observations have been made in sheep, which is the species most often used to study the effect of endotoxin in the ruminant brain (Karsch et al. 2002). ...
Chapter
This book chapter describes the causes, consequences, and treatment of postpartum uterine diseases, such as metritis and endometritis. Please REQUEST A COPY from me if you want to read more.
... Additionally, the increased inflammation in this postpartum period can be detrimental to intake, increasing the NEB [45]. The acute inflammatory response from clinical and subclinical postpartum disorders reduces serum PON1 activity and may affect the expression of key enzymes involved in ovarian steroidogenesis, with a negative impact on final follicular development, especially if the inflammatory process persists for longer periods [46,47]. In a previous study by our group, cows that ovulated earlier in the postpartum period tended to have higher serum PON1 activity [16] compared to cows that remained anovulatory. ...
Article
Paraoxonase 1 (PON1) is a negative acute phase plasma protein synthesized by the liver that has anti-oxidant activity. The aim of this study was to evaluate the association of single nucleotide polymorphisms (SNPs) in the PON1 promoter region with plasma PON1 activity and fertility in Holstein dairy cows. Sixty-eighty Holstein cows were used in this initial investigative study. Blood samples were collected weekly beginning 28 days prior to expected calving, twice weekly in week 1 and 2 postpartum, and then once weekly through 6 weeks postpartum for plasma PON1 activity analysis. Cows were synchronized for ovulation and timed AI at 63–70 DIM using an Ovsynch program. Pregnancy diagnosis was confirmed by rectal palpation and reproductive performance data was recorded until 210 DIM. DNA was extracted from blood of each cow and a fragment of proximal PON1 gene promoter was sequenced. Seven single nucleotide polymorphisms (SNPs) were identified in the promoter region of the PON1 gene at positions −22, −105, −176, −221, −392, −611 and −676, six of which were significantly associated with plasma PON1 activity level. The SNPs −221 and −392 were significantly associated with both plasma PON1 activity and the calving to conception interval (P < 0.05) with no significant effect on calving to first ovulation interval. In conclusion, the genotypes associated with higher plasma PON1 activity in SNP locations −221 and −392 were also associated with a reduced calving to conception interval in this study set of cows. These SNPs may provide novel genetic markers for improved fertility in future larger studies in dairy cows.
... Furthermore, instillation of LPS in the mammary gland consistently increases systemic concentrations of cytokine tumor necrosis factor alpha (TNFA; Blum et al. 2000). In addition, exogenous LPS reduced fertility due to impairment of ovarian follicular development and ovulation (Suzuki et al. 2001, Lavon et al. 2008, Williams et al. 2008. The LH peak was significantly retarded or completely inhibited in cows given LPS during proestrus (Suzuki et al. 2001). ...
... In postpartum cows, LPS in the uterus suppresses the LH surge and prevents ovulation (14). In addition, during the follicular phase, LPS decreases LH pulse frequency, decreases estradiol, and interrupts the LH surge and ovulation in cattle (145,146). However, the peripheral plasma concentrations of FSH are unaffected by uterine disease in cattle, so that recurrent waves of follicles develop in the ovary, even during uterine disease (7). ...
Article
Bacteria are ubiquitous in the uterus of cattle after parturition, but 50 years ago, cows tolerated these bacteria and few animals developed uterine disease. Now, up to 40% of dairy cattle develop postpartum uterine disease. Uterine disease causes infertility by compromising not only the function of the endometrium but also the ovary. Animals defend themselves against pathogens using tolerance and resistance mechanisms. Tolerance is the ability to limit the disease severity induced by a given pathogen burden. Resistance is the ability to limit the pathogen burden, and is usually the function of immunity. Cellular barriers, mucus, and tissue repair contribute to tolerance in the endometrium. However, once tolerance is overcome, endometrial cells also have roles in resistance to pathogens, with innate immunity driving the production of cytokines, chemokines and prostaglandins. We propose that failures in endometrial tolerance to pathogenic bacteria and the subsequent innate immune response shape postpartum uterine disease.
... In this way, Piersanti et al. (2019) found that metritis causes persistent changes in the follicular granulosa cells during follicle development, as indicated by changes in their transcriptome profile even several weeks after resolution of disease and parturition (Piersanti et al. 2019). In cows and sheep, uterine infection may affect the endocrine axis by affecting the pulsefrequency release of gonadotrophin-releasing hormone and luteinising hormone (LH), delaying the LH surge, decreasing estradiol secretion and leading to anovulation (Suzuki et al. 2001;Lavon et al. 2008). These hormonal imbalances have been related to the capacity of the lipopolysaccharides of pathogens to suppress the expression of genes encoding gonadotrophin-releasing hormone receptors in the medial preoptic area and median eminence (Herman et al. 2013). ...
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This study was aimed to assess the effect of adding clinoptilolite in the diet on uterine health and reproductive performance in multiparous lactating dairy cows managed in a tropical pasture-based system above 2500 meters of altitude. Seventy-seven multiparous Holstein crossbred cows were allocated randomly into two groups: clinoptilolite supplemented cows (CLG, n = 42) and non-supplemented cows as control (CG, n = 35). Cows from CLG were supplemented with clinoptilolite from 30 days (50 g/cow/day) before to 60 days after calving (200 g/cow/day). Data were analyzed by general linear model, least squares means and chi-square test of SAS. In CLG cows, percentages of uterine PMN leukocytes (P<0.0001) and proportion of subclinical endometritis (P=0.0187) were lower than in CG. The interval calving to first corpus luteum was shorter (P=0.0759) in CLG than CG, and calving to first service interval was similar between treatments. Cows from CLG became pregnant 35 days earlier than CG cows (P=0.0224). In conclusion, daily addition of clinoptilolite in the diet decreased the proportion of cows with subclinical endometritis and shortened the interval from calving to conception in lactating dairy cows.
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Endotoxemia can be caused by obesity, environmental chemical exposure, abiotic stressors, and bacterial infection. Circumstances that deleteriously impact intestinal barrier integrity can induce endotoxemia and controlled experiments have identified negative impacts of lipopolysaccharide (LPS; an endotoxin mimetic) on folliculogenesis, puberty onset, estrus behavior, ovulation, meiotic competence, luteal function and ovarian steroidogenesis. In addition, neonatal LPS exposures have transgenerational female reproductive impacts, raising concern about early life contacts to this endogenous reproductive toxicant. Aims of this review are to identify physiological stressors causing endotoxemia, to highlight potential mechanism(s) by which LPS compromises female reproduction, and identify knowledge gaps regarding how acute and/or metabolic endotoxemia influence(s) female reproduction.
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The means by which stress influences reproduction is not clearly understood, but may involve a number of endocrine, paracrine and neural systems. Stress impacts on the reproductive axis at the hypothalamus (to affect GnRH secretion) and the pituitary gland (to affect gonadotrophin secretion), with direct effects on the gonads being of less importance. Different stressors have different effects and there are differences in response to short- and long-term stress. Many short-term stresses fail to affect reproduction and there are reports of stimulatory effects of some 'stressors'. There are species differences in the way that specific stressors affect reproduction. Sex differences in the effects of a particular stressor have been delineated and these may relate to effects of stress at different levels of the hypothalamo-pituitary axis. The significance of stress-induced secretion of cortisol varies with species. In some instances, there appears to be little impact of short-term increases in cortisol concentrations and protracted increases in plasma concentration seem to be required before any deleterious effect on reproduction is apparent. Issues of sex, sex steroid status, type of stressor and duration of stress need to be considered to improve understanding of this issue.
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Two experiments were conducted to investigate endocrine mechanisms by which the immune/inflammatory stimulus endotoxin disrupts the follicular phase of the estrous cycle of the ewe. In both studies, endotoxin was infused i.v. (300 ng/kg per hour) for 26 h beginning 12 h after withdrawal of progesterone to initiate the follicular phase. Experiment 1 sought to pinpoint which endocrine step or steps in the preovulatory sequence are compromised by endotoxin. In sham-infused controls, estradiol rose progressively from the time of progesterone withdrawal until the LH/FSH surges and estrous behavior, which began approximately 48 h after progesterone withdrawal. Endotoxin interrupted the preovulatory estradiol rise and delayed or blocked the LH/FSH surges and estrus. Experiment 2 tested the hypothesis that endotoxin suppresses the high-frequency LH pulses necessary to stimulate the preovulatory estradiol rise. All 6 controls exhibited high-frequency LH pulses typically associated with the preovulatory estradiol rise. As in the first experiment, endotoxin interrupted the estradiol rise and delayed or blocked the LH/FSH surges and estrus. LH pulse patterns, however, differed among the six endotoxin-treated ewes. Three showed markedly disrupted LH pulses compared to those of controls. The three remaining experimental ewes expressed LH pulses similar to those of controls; yet the estradiol rise and preovulatory LH surge were still disrupted. Our results demonstrate that endotoxin invariably interrupts the preovulatory estradiol rise and delays or blocks the subsequent LH and FSH surges in the ewe. Mechanistically, endotoxin can interfere with the preovulatory sequence of endocrine events via suppression of LH pulsatility, although other processes such as ovarian responsiveness to gonadotropin stimulation appear to be disrupted as well.
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In this study we examined, in two experiments, patterns of follicular development and dominance under conditions of heat stress. Estrous cycles were programmed to include two follicular waves (wave 1 and 2). On Day 1 of the estrous cycle (Day 0 = estrus), cows were assigned randomly to cooled (C; n = 6) or heat-stressed (H; n = 6) groups. In experiment 1, on Day 12 prostaglandin (PG) F2 alpha was injected and a controlled intravaginal drug release device (1.9 g progesterone) was inserted (this was removed on Day 17). In experiment 2, PGF 2 alpha was injected on Day 14. Ovarian structures were examined daily by ultrasonography, and blood samples were collected at each scanning. Cycle lengths were 20 and 17 days in experiments 1 and 2, respectively. Mean maximal body temperatures were higher (p < 0.01) in H (40.3 degrees C) than in C (38.8 degrees C) cows. In experiment 1, the rate of increase in number of large follicles (> or = 10 mm) was greater in H than in C cows (p < 0.01), resulting in 53% more large follicles in H cows during wave 1; this was associated with a lower (p < 0.05) number of medium-sized (6-9 mm) follicles between Days 7 and 10 of the cycle. Heat stress hastened (p < 0.02) the decrease in size of the first-wave dominant follicle and hastened (p < 0.01) the emergence of the second dominant (preovulatory) follicle by 2 days.(ABSTRACT TRUNCATED AT 250 WORDS)
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Prolonging the lifespan of bovine follicles is known to result in reduced fertility after ovulation and insemination. In this study, the effect of prolonged development of follicles on oocyte viability was examined. In Expt 1, six cows in the aspirated-prolonged-follicle group received a vaginal progesterone releasing device on day 4 of the oestrous cycle (day 1 = ovulation) and prostaglandin F2 alpha (40 mg) on day 6. Ultrasound-guided follicular aspiration was performed on day 13. Six cows in the aspirated-growing-follicle group received prostaglandin F2 alpha on day 6, and follicular aspiration on day 7. In Expt 2, all cows were stimulated with 36 mg FSH-P to develop multiple large follicles for study. Three cows in the prolonged-multiple-follicle group received the same treatment as did cows in Expt 1, but were ovariectomized on day 13. Three cows in the growing-multiple-follicle group received prostaglandin F2 alpha on day 6 and were ovariectomized on day 7. Oocytes recovered in both experiments were stained to reveal the stage of nuclear development. All oocytes from aspirated-prolonged and prolonged-multiple follicles showed expanded cumulus cells and condensed chromatin dispersed in the ooplasm, with possible germinal vesicle breakdown. Oocytes from aspirated-growing and growing-multiple follicles showed compact cumulus cells and an intact germinal vesicle. Plasma concentrations of oestradiol in both growing follicle groups increased until oocyte recovery. Oestradiol in the aspirated-prolonged-follicle group increased after luteolysis on day 6 and remained high until follicular aspiration. In contrast, in the FSH-stimulated prolonged-multiple-follicle group, oestradiol fell to trace amounts on day 8 and remained low. Oestradiol concentrations in follicular fluid were consistent with plasma concentrations for all groups. Bovine oocytes from prolonged dominant follicles undergo premature maturation in vivo, which perhaps accounts for the poor fertility observed in other studies when oestrous synchronization with progestins prolongs follicle lifespan.
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During in-vitro fertilization (IVF) cycles, a large bolus of human chorionic gonadotrophin (HCG) is used to induce periovulatory events, but the efficacy of lower doses is undefined. Following follicular stimulation in rhesus monkeys, oocyte nuclear maturation, IVF, granulosa cell luteinization and corpus luteum function were compared after injection of 100, 300 or 1000 IU recombinant HCG or 1000 IU urinary HCG. Bioactive HCG rose to peak concentrations within 2 h that were proportional to the dose administered (100 < 300 < 1000 IU, recombinant HCG = urinary HCG). The duration of surge values (>100 ng/ml) was also dose-dependent (0 h, 100 IU; 24 h, 300 IU; >48 h, 1000 IU, recombinant and urinary HCG). While the proportions of oocytes resuming meiosis and undergoing IVF were similar among groups, fewer animals yielded fertilizable oocytes following 100 and 300 IU (five of nine) compared to 1000 IU recombinant and urinary HCG (nine of 10). Peak values of serum progesterone in the luteal phase were similar, but declined 2 days earlier after 100 and 300 IU relative to 1000 IU recombinant and urinary HCG. Thus, 3-10 fold lower doses of HCG elicit low amplitude surges of short duration that induce periovulatory events such as re-initiation of oocyte meiosis and granulosa cell luteinization. However, oocyte fertilization and luteal function may optimally require surges of higher amplitude and longer duration similar to those produced by standard doses of 1000 IU recombinant or urinary HCG.
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Three experiments were conducted to investigate whether the immune/inflammatory stimulus endotoxin disrupts the estradiol-induced LH surge of the ewe. Ovariectomized sheep were set up in an artificial follicular phase model in which luteolysis is simulated by progesterone withdrawal and the follicular phase estradiol rise is reproduced experimentally. In the first experiment, we tested the hypothesis that endotoxin interferes with the estradiol-induced LH surge. Ewes were either infused with endotoxin (300 ng/kg/h, i.v.) for 30 h beginning at onset of a 48-h estradiol stimulus or sham infused as a control. Endotoxin significantly delayed the time to the LH surge (P < 0.01), but did not alter surge amplitude, duration, or incidence. The second experiment tested the hypothesis that the delaying effects of endotoxin on the LH surge depend on when endotoxin is introduced relative to the onset of the estradiol signal. Previous work in the ewe has shown that a 14-h estradiol signal is adequate to generate GnRH and LH surges, which begin 6-8 h later. Thus, we again infused endotoxin for 30 h, but began it 14 h after the onset of the estradiol signal. In contrast to the first experiment, endotoxin given later had no effect on any parameter of the LH surge. In the third experiment, we tested the hypothesis that endotoxin acts during the first 14 h to disrupt the initial activating effects of estradiol. Estradiol was delivered for just 14 h, and endotoxin was infused only during this time. Under these conditions, endotoxin blocked the LH surge in five of eight ewes. In a similar follow-up study, endotoxin again blocked the LH surge in six of seven ewes. We conclude that endotoxin can disrupt the estradiol-induced LH surge by interfering with the early activating effects of the estradiol signal during the first 14 h (reading of the signal). In contrast, endotoxin does not disrupt later stages of signal processing (i.e. events during the interval between estradiol signal delivery and surge onset), nor does it prevent actual hormonal surge output. Thus, endotoxin appears to disrupt estrogen action per se rather than the release of GnRH or LH at the time of the surge.
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The aim of this study was to elucidate the mechanism(s) involved in stress-induced subfertility by examining the effect of 4 h transport on surge and pulsatile LH secretion in intact ewes and ovariectomized ewes treated with steroids to induce an artificial follicular phase (model ewes). Transport caused a greater delay in the onset of the LH surge in nine intact ewes than it did in ten ovariectomized ewes (intact: 41.0 +/- 0.9 h versus 48.3 +/- 0.8 h, P < 0.02; ovariectomized model: 40.8 +/- 0.6 h versus 42.6 +/- 0.5 h, P < 0.02). Disruption of the hypothalamus-pituitary endocrine balance in intact ewes may have reduced gonadotrophin stimulation of follicular oestradiol production which had an additional effect on the LH surge mechanism. In the ovariectomized model ewes, this effect was masked by the exogenous supply of oestradiol. However, in these model ewes, there was a greater suppression of maximum LH surge concentrations (intact controls: 29 +/- 4 ng ml-1 versus intact transported 22 +/- 5 ng ml-1, P < 0.02; ovariectomized model controls: 35 +/- 7 ng ml-1 versus model transported 15 +/- 2 ng ml-1, P < 0.02). Subsequent exposure to progesterone for 12 days resulted in the resumption of a normal LH profile in the next follicular phase, indicating that acute stress leads to a temporary endocrine lesion. In four intact ewes transported in the mid-follicular phase, there was a suppression of LH pulse amplitude (0.9 +/- 0.3 versus 0.3 +/- 0.02 ng ml-1, P < 0.05) but a statistically significant effect on pulse frequency was not observed (2.0 +/- 0.4 versus 1.7 +/- 0.6 pulses per 2 h). In conclusion, activation of the hypothalamus-pituitary-adrenal axis by transport in the follicular phase of intact ewes interrupts surge secretion of LH, possibly by interference with LH pulsatility and, hence, follicular oestradiol production. This disruption of gonadotrophin secretion will have a major impact on fertility.
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Stress-like concentrations of cortisol increase the negative feedback potency of oestradiol in castrated male sheep. A similar cortisol-dependent response in female sheep might be expected to suppress gonadotrophin secretion and impair follicular development and ovulation. The oestrous activity of 21 female sheep was synchronized using progestogen-treated vaginal pessaries to test this hypothesis. Stress-like concentrations of cortisol (60-70 ng ml-1) were established by continuous infusion of cortisol (80 micrograms kg-1 h-1; n = 13) beginning 5 days before, and continuing for 5 days after, pessary removal. Control animals (n = 8) received a comparable volume of vehicle (50% ethanol-saline) over the 10 day infusion period. Serum concentrations of oestradiol increased progressively in control sheep during the 48 h immediately after pessary removal. This increase in serum oestradiol was blocked or significantly attenuated in sheep receiving stress-like concentrations of cortisol. Preovulatory surge-like secretion of LH was apparent in control animals 58.5 +/- 2.1 h after pessary removal. In contrast, surge-like secretion of LH was not observed during the 5 days after pessary removal in 54% (7 of 13) of sheep receiving cortisol. Moreover, the onset of the surge was significantly delayed in the cortisol-treated ewes that showed surge-like secretion of LH during the infusion period. The ability of episodic pulses of exogenous GnRH to override the anti-gonadal effect of cortisol was examined in a second study. Oestrous activity of 12 ewes was synchronized using progestogen-containing pessaries as described above. Ewes were randomly assigned to one of three treatment groups (n = 4 ewes per group). Animals received cortisol (100 micrograms kg-1 h-1; groups 1 and 2) or a comparable volume of vehicle (group 3) beginning 5 days before, and continuing for 2 days after, pessary removal. Pulses of GnRH (4 ng kg-1 h-1, i.v.; group 1) or saline (groups 2 and 3) at 1 h intervals were initiated at pessary removal and continued for 48 h. Serum concentrations of oestradiol were not significantly increased after pessary removal in sheep receiving cortisol alone. Conversely, serum concentrations of oestradiol increased progressively during the 48 h after pessary removal in control ewes and in ewes receiving cortisol and GnRH. At the end of infusion, serum concentrations of oestradiol did not differ (P > 0.05) between control (7.7 +/- 0.8 pg ml-1) ewes and ewes receiving cortisol and episodic GnRH (6.4 +/- 1.3 pg ml-1). Moreover, these values were significantly greater (P < 0.05) than the serum concentrations of oestradiol in animals receiving cortisol (1.0 +/- 0.4 pg ml-1) alone. Collectively, these data indicate stress-like concentrations of cortisol block or delay follicular development and the preovulatory surge of LH in sheep. In addition, episodic GnRH overrides cortisol-induced delay in follicular maturation.
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The secretion of glucocorticoids (GCs) is a classic endocrine response to stress. Despite that, it remains controversial as to what purpose GCs serve at such times. One view, stretching back to the time of Hans Selye, posits that GCs help mediate the ongoing or pending stress response, either via basal levels of GCs permitting other facets of the stress response to emerge efficaciously, and/or by stress levels of GCs actively stimulating the stress response. In contrast, a revisionist viewpoint posits that GCs suppress the stress response, preventing it from being pathologically overactivated. In this review, we consider recent findings regarding GC action and, based on them, generate criteria for determining whether a particular GC action permits, stimulates, or suppresses an ongoing stress-response or, as an additional category, is preparative for a subsequent stressor. We apply these GC actions to the realms of cardiovascular function, fluid volume and hemorrhage, immunity and inflammation, metabolism, neurobiology, and reproductive physiology. We find that GC actions fall into markedly different categories, depending on the physiological endpoint in question, with evidence for mediating effects in some cases, and suppressive or preparative in others. We then attempt to assimilate these heterogeneous GC actions into a physiological whole.
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The means by which stress influences reproduction is not clearly understood, but may involve a number of endocrine, paracrine and neural systems. Stress impacts on the reproductive axis at the hypothalamus (to affect GnRH secretion) and the pituitary gland (to affect gonadotrophin secretion), with direct effects on the gonads being of less importance. Different stressors have different effects and there are differences in response to short- and long-term stress. Many short-term stresses fail to affect reproduction and there are reports of stimulatory effects of some 'stressors'. There are species differences in the way that specific stressors affect reproduction. Sex differences in the effects of a particular stressor have been delineated and these may relate to effects of stress at different levels of the hypothalamo-pituitary axis. The significance of stress-induced secretion of cortisol varies with species. In some instances, there appears to be little impact of short-term increases in cortisol concentrations and protracted increases in plasma concentration seem to be required before any deleterious effect on reproduction is apparent. Issues of sex, sex steroid status, type of stressor and duration of stress need to be considered to improve understanding of this issue.
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The effects of two methods of inducing low progesterone concentrations on the shape of the plasma progesterone curve and on follicular characteristics in lactating cows were studied. A low ascending progesterone curve was elicited by three PGF2alpha injections on d 3 to 4 of the estrous cycle; a low constant curve by induction of corpus luteum regression on d 6 and insertion of two progesterone-containing intravaginal devices from d 6 to 15 of the cycle. Plasma progesterone concentration was highest in the untreated control group, intermediate in low ascending group, and lowest in the low constant group. On d 15, both control and low ascending groups had one large healthy and one large atretic follicle, suggesting a turnover of follicular waves; in the low constant group, the presence of only one very large healthy follicle indicated follicular persistence. Estradiol concentration in the follicular fluid and its production by granulosa cells were highest in the low constant, intermediate in the low ascending, and lowest in the control group. Androstenedione concentration in the follicular fluid and its production by theca cells were higher in the low constant than in the low ascending and control groups. The results indicate that the low ascending progesterone curve affected follicular development and steroidogenesis differently from the low constant curve. We suggest that the low ascending curve mimics the effects of naturally occurring low plasma progesterone concentrations better, and it might, therefore, be used as a model for studying the effects of low plasma progesterone on fertility.
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Bacterial endotoxin (lipopolysaccharide), a commonly used model of immune/inflammatory stress, inhibits reproductive neuroendocrine activity and concurrently induces a profound stimulation of the hypothalamo-pituitary-adrenal axis. We employed two approaches to test the hypothesis that enhanced secretion of cortisol mediates endotoxin-induced suppression of pulsatile GnRH and LH secretion in the ovariectomized ewe. First, we mimicked the endotoxin-induced increase in circulating cortisol by delivering the glucocorticoid in the absence of the endotoxin challenge. Within 1-2 h, experimentally produced increments in circulating cortisol suppressed pulsatile LH secretion in a dose-dependent fashion. Second, we blocked the endotoxin-induced stimulation of cortisol secretion using the drug metyrapone, which inhibits the 11-beta hydroxylase enzyme necessary for cortisol biosynthesis. In the absence of a marked stimulation of cortisol secretion, endotoxin still profoundly inhibited pulsatile GnRH and LH secretion. We conclude that, although enhanced cortisol secretion may contribute to endotoxin-induced suppression of reproductive neuroendocrine activity, the marked stimulation of the glucocorticoid is not necessary for this response. Our findings are consistent with the hypothesis that immune/inflammatory stress inhibits reproductive neuroendocrine activity via more than one inhibitory pathway, one involving enhanced secretion of cortisol and the other(s) being independent of this glucocorticoid.
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Short fertile half-lives of the male and female gametes in the female tract necessitate accurate timing of artificial insemination. We examined the possible association between extension of the estrus to ovulation (E-O) interval and alterations in concentrations of estradiol, progesterone, and the preovulatory LH surge before estrus and ovulation. High-yielding Holstein cows (n = 74 from a total of 106) were synchronized and were examined around the time of the subsequent estrus. They were observed continuously for estrual behavior. Blood samples were collected before and after estrus, and ultrasound checks for ovulation were made every 4 h. About three-quarters of the cows exhibited short (but normal) E-O intervals of 22 to 25 h (25%) or normal intervals of 25 to 30 h (47%); 17% of them displayed a long (but normal) E-O interval of 31 to 35 h, and about 10% exhibited a very long E-O interval of 35 to 50 h. Extended E-O interval comprised estrus-to-LH surge and LH surge-to-ovulation intervals that were both longer than normal. Pronounced changes in hormonal concentrations were noted before ovulation in the very long E-O interval group of cows: progesterone and estradiol concentrations were reduced, and the preovulatory LH peak surge was markedly less than in the other 3 groups. Postovulation progesterone concentrations during the midluteal phase were lesser in the very long and the long E-O interval groups compared with those in the short and normal interval groups. Season, parity, milk yield, and body condition did not affect the estrus to LH surge, LH surge to ovulation, and E-O intervals. The results indicate an association between preovulatory-reduced estradiol concentrations and a small preovulatory LH surge, on the one hand, and an extended E-O interval, on the other hand. Delayed ovulation could cause nonoptimal timing of AI, a less than normal preovulatory LH surge that may be associated with suboptimal maturation of the oocyte before ovulation, or reduced progesterone concentrations before and after ovulation. All may be factors associated with poor fertility in cows with a very long E-O interval.
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The dynamics of blood neutrophil acyloxyacyl hydrolase (AOAH) activity, the appearance of endotoxin (lipopolysaccharide, LPS) in blood and the role of blood neutrophil AOAH in the severity of Escherichia coli and endotoxin mastitis were investigated in early postpartum dairy cows experimentally challenged with either endotoxin (n = 6) or E. coli (n = 6). The AOAH activity of blood neutrophils started to decrease significantly at post challenge hours (PCH) 6-24 and 12-24 in the endotoxin and E. coli-challenged groups, respectively; it returned to pre-challenged values at PCH 48 in both endotoxin- and E. coli-challenged groups. The cows were classified as moderate and severe responders according to milk production loss in the non-challenged quarters at PCH 48. There were no severe responders in the endotoxin-challenged group. In the E. coli-challenged group, only 1 severe responder was identified. The pre-challenge neutrophil AOAH activity of the severe responder was approximately 30% lower than that of moderate responders. No LPS was detected in the plasma of endotoxin-challenged cows; neither was it found in the plasma of moderate responders in the E. coli-challenged group at any PCH. However, at PCH 6, a remarkable amount of LPS was detected in the plasma of the severe responder from the E. coli-challenged group. Furthermore, neutrophil AOAH activity was increased by approximately 70% in the severe responder at PCH 6, but it increased by only approximately 15% in moderate responders. This was followed by a decreased neutrophil AOAH activity at PCH 12-24 and 24-72 in moderate and severe responders, respectively; the decreased AOAH activity at those PCH was more pronounced in the severe responder. The pronounced decreased neutrophil AOAH activity during mastitis often coincided with extreme leukopenia, neutropenia and a maximal number of immature neutrophils in the blood. Our results demonstrate that a decrease in neutrophil AOAH activity results in the appearance of LPS in the blood, and low blood neutrophil deacylation activity could be considered as a risk factor for severe clinical coliform mastitis.
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Immune/inflammatory challenges, such as bacterial endotoxin, disrupt gonadotropin secretion and ovarian cyclicity. We previously determined that endotoxin can block the estradiol-induced LH surge in the ewe. Here, we investigated mechanisms underlying this suppression. First, we tested the hypothesis that endotoxin blocks the estradiol-induced LH surge centrally, by preventing the GnRH surge. Artificial follicular phases were created in ovariectomized ewes, and either endotoxin or vehicle was administered together with a surge-inducing estradiol stimulus. In each ewe in which endotoxin blocked the LH surge, the GnRH surge was also blocked. Given this evidence that endotoxin blocks the estradiol-induced LH surge at the hypothalamic level, we began to assess underlying central mechanisms. Specifically, in view of the prior demonstration that prostaglandins mediate endotoxin-induced suppression of pulsatile GnRH secretion in ewes, we tested the hypothesis that prostaglandins also mediate endotoxin-induced blockade of the surge. The prostaglandin synthesis inhibitor flurbiprofen was delivered together with endotoxin and the estradiol stimulus. Although flurbiprofen abolished endotoxin-induced fever, which is a centrally generated, prostaglandin-mediated response, it failed to reverse blockade of the LH surge. Collectively, these results indicate endotoxin blocks the LH surge centrally, suppressing GnRH secretion via a mechanism not requiring prostaglandins. This contrasts with the suppressive effect of endotoxin on GnRH pulses, which requires prostaglandins as intermediates.
Article
In this study we examined, in two experiments, patterns of follicular development and dominance under conditions of heat stress. Estrous cycles were programmed to include two follicular waves (wave 1 and 2). On Day 1 of the estrous cycle (Day 0 = estrus), cows were assigned randomly to cooled (C; n = 6) or heat-stressed (H; n = 6) groups. In experiment 1, on Day 12 prostaglandin (PG) F2 alpha was injected and a controlled intravaginal drug release device (1.9 g progesterone) was inserted (this was removed on Day 17). In experiment 2, PGF 2 alpha was injected on Day 14. Ovarian structures were examined daily by ultrasonography, and blood samples were collected at each scanning. Cycle lengths were 20 and 17 days in experiments 1 and 2, respectively. Mean maximal body temperatures were higher (p < 0.01) in H (40.3 degrees C) than in C (38.8 degrees C) cows. In experiment 1, the rate of increase in number of large follicles (> or = 10 mm) was greater in H than in C cows (p < 0.01), resulting in 53% more large follicles in H cows during wave 1; this was associated with a lower (p < 0.05) number of medium-sized (6-9 mm) follicles between Days 7 and 10 of the cycle. Heat stress hastened (p < 0.02) the decrease in size of the first-wave dominant follicle and hastened (p < 0.01) the emergence of the second dominant (preovulatory) follicle by 2 days.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The production of TNF-alpha, IL-1, and IL-6 was measured in mice after bolus i.v. Escherichia coli O111 LPS injections and during bacteremia induced either by bolus i.v. or by i.p. challenges of live E. coli O111. High but transient TNF-alpha peaks were observed after bolus i.v. LPS or bacterial challenges. In contrast, the levels during lethal peritonitis increased progressively to values 50- to 100-fold lower than the peak values observed after i.v. injections, and remained sustained until death. Whereas after i.v. challenge with 1000 LD50 of LPS, anti-TNF-alpha antibody fully protected mice from death and reduced serum IL-1 and IL-6 levels, anti-TNF-alpha antibody did not improve the survival of mice nor reduced serum IL-1 and IL-6 levels after i.p. bacterial challenge. In contrast to anti-TNF-alpha antibodies, anti-LPS antibodies were protective in the peritonitis model. Protection was accompanied by a striking reduction of bacterial numbers and of TNF-alpha, IL-1, and IL-6 levels in the serum, but the levels of these cytokines were only marginally affected in the peritoneal lavage fluid. This latter observation demonstrates that the local peritoneal cytokines did not diffuse readily into the circulation, thus suggesting that at least part of the circulating cytokines are produced systemically. In conclusion, the striking differences between cytokine profiles as well as the divergent efficacy of anti-TNF-alpha antibody after i.v. bolus and after i.p. challenges suggest that TNF-alpha may not be as important in the pathogenesis of lethal peritonitis than after lethal acute bacteremia.
Article
Alterations of immune activity are often accompanied by reproductive disorders. Because interleukins mediate the host's response to immune activation, we first examined the effect of the central injection of several lymphokines on LH secretion by gonadectomized rats. We then studied the ability of the most potent lymphokine in this system, interleukin-1 beta (Il-1 beta), to interfere with the proestrous LH surge and ovulation in the intact female rat as well as the dependence of this effect on the activation of opiate receptors. Finally, we investigated the possibility that increased brain levels of Ils, as induced by the central administration of a bacterial endotoxin, might also alter the normal ovulatory process. After intracerebroventricular (icv) injection, Il-1 beta, Il-6, and tumor necrosis factor all lowered plasma LH levels in castrated rats. On a molar basis, Il-1 beta was the most potent inhibitor of LH secretion. In gonadectomized animals, 2.5 and 10 ng Il-1 beta administered icv significantly (P less than or equal to 0.01) decreased plasma LH levels for 6 h, while the effect of 40 ng lasted up to 12 h. By contrast, FSH secretion was only measurably altered by 40 ng Il-1 beta 8 and 12 h posttreatment. In intact cycling female rats, icv injection of 40 ng Il-1 beta or 400 ng Il-1 alpha at 0830 h on the morning of proestrus significantly (P less than 0.01 and P less than 0.05, respectively) interfered with the proestrous surge of LH. In contrast, the peripheral administration of either lymphokine was without measurable effect. Centrally injected Il-1 beta (40 ng at 0830 h on proestrus) also blocked ovulation in most animals, while a dose of 25 ng injected iv was ineffective. Finally, we observed that the icv injection of endotoxin (a lipopolysaccharide), also interfered with ovulation. The possible involvement of opiate-dependent pathways in mediating the inhibitory action of Il-1 beta on reproductive processes was tested by implanting naloxone pellets 16-24 h before lymphokine treatment. The pellets, which released 200, 400, or 800 micrograms naloxone/h (corresponding to approximately 0.6, 1.32, or 2.64 mg/kg BW.h), had no effect on ovulation by themselves. When given before icv Il-1 beta, all naloxone regimens countered the effect of the cytokine, with the 800-micrograms/h dose restoring ovulation in eight of nine rats.(ABSTRACT TRUNCATED AT 400 WORDS)
Article
Twenty-one, middle to late lactation Holstein cows were assigned to one of three treatments in a completely randomized design to examine physiological changes associated with intramammary or intravenous administration of Escherichia coli endotoxin. Treatments were 1) Hank's balanced salt solution infusion in two contralateral quarters (control), 2) E. coli endotoxin infusion in two contralateral quarters, and 3) intravenous infusion of E. coli endotoxin. Blood was sampled and rectal temperature was measured at 30-min intervals. Endotoxin treatment was at 0900 h and sampling continued until 1700 h. Serum prolactin, cortisol, and 13,14-dihydro-15-keto-prostaglandin F2 alpha were measured. A pyretic response was observed in intravenous and intramammary treatment groups after endotoxin treatment. Response peak was higher (41.1 vs. 40.3 degrees C) and occurred later (6 vs. 4.5 h posttreatment) in the intramammary than the intravenous treatment group. Significant prolactin peaks were observed also in intravenous and intramammary endotoxin treatment groups. Prolactin peaked higher (288 vs. 112 ng/ml) and occurred sooner (1 vs. 4 h posttreatment) in the intravenous than in the intramammary treatment group. Cortisol followed a trend similar to prolactin. Cortisol peaked higher (100 vs. 82 ng/ml) and sooner (2.5 vs. 4.5 h posttreatment) in the intravenous than in the intramammary treatment group. Concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha increased rapidly posttreatment in the intravenous group only.
Article
This study investigated whether the stress associated with a 30-minute journey in a truck could distort the oestradiol-induced surge of luteinising hormone (LH) in dairy cows. Altogether 20 journeys were monitored, 16 to 18 hours after intramuscular administration of 1 mg oestradiol benzoate (OE2). Plasma cortisol concentration was elevated (P less than 0.001) within 30 minutes of the start of each journey, even when the journey was repeated at about weekly intervals, indicating a lack of habituation. The LH surge in response to 11 OE2 treatments in nine non-cycling cows within 30 days after calving was either absent (one cow) or significantly delayed, of shorter duration or of lesser amplitude following transport, compared with untransported OE2-treated controls. However, in six cycling cows, 58 days or more after calving, transport affected the LH surge only once. Even in these cows, the LH surge did not start until the cortisol concentration returned to normal, which may suggest a transient postponement of the LH surge by transport. In conclusion, transport impaired the LH surge in early post partum cows with little or no effect after ovarian cyclicity was resumed. It is hypothesised that endocrine events leading to the onset of the LH surge are more vulnerable to stressors in early post partum cows and in the natural situation this might be responsible for the occurrence of anovulation and cystic ovarian disease.
Article
A study was conducted to test the hypothesis that high cortisol concentrations associated with products of infections (endotoxin) cause derangement in the neuroendocrine mechanism controlling ovulation in heifers. Eight Holstein heifers were given 2 injections of prostaglandin (PG), 11 days apart, to synchronize estrus. Starting from 25 hours after the second injection of PG (PG-2), the uterus of each heifer was infused with 5 ml of pyrogen-free water (control, n = 3) or Escherichia coli endotoxin (5 micrograms/kg of body weight) in 5 ml of pyrogen-free water (treated, n = 5), once every 6 hours for 10 treatments. Blood samples were obtained every 15 minutes via indwelling jugular catheter for an hour before and 2 hours after each infusion, then hourly until an hour before the next infusion. Ultrasonography of the ovaries was performed every 12 hours, starting 24 hours after PG-2 injection until 96 hours after PG-2 injection. Serum concentrations of luteinizing hormone and cortisol were determined by validated radioimmunoassays. Changes in cortisol concentrations were not detected in control heifers with preovulatory luteinizing hormone surges at 60 to 66 hours after PG-2 injection, followed by ovulations 72 to 96 hours after PG-2 was injected. None of the treated heifers ovulated, and the resulting follicular cysts (14 to 18 mm diameter) persisted for 7 to 21 days. In all treated heifers, serum cortisol concentrations increased (4- to 10-fold) during the first 2 hours after each infusion and then decreased gradually until the next infusion. Luteinizing hormone concentrations remained at baseline values throughout the treatment period in all treated heifers.(ABSTRACT TRUNCATED AT 250 WORDS)