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Journal of Developmental
Origins of Health and Disease
www.cambridge.org/doh
Original Article
Cite this article: Sutovska H, Molcan L,
Koprdova R, Piesova M, Mach M, and Zeman M.
(2021) Prenatal hypoxia increases blood
pressure in male rat offspring and affects their
response to artificial light at night. Journal of
Developmental Origins of Health and Disease 12:
587–594. doi: 10.1017/S2040174420000963
Received: 3 April 2020
Revised: 24 July 2020
Accepted: 15 September 2020
First published online: 28 October 2020
Keywords:
Blood pressure; heart rate; prenatal hypoxia;
artificial light at night
Address for correspondence:
Lubos Molcan, Department of Animal
Physiology and Ethology, Faculty of Natural
Sciences, Comenius University in Bratislava,
Ilkovicova 6, Bratislava, Slovakia.
Email: lubos.molcan@uniba.sk
© The Author(s), 2020. Published by Cambridge
University Press in association with
International Society for Developmental
Origins of Health and Disease.
Prenatal hypoxia increases blood pressure in
male rat offspring and affects their response
to artificial light at night
Hana Sutovska1, Lubos Molcan1, Romana Koprdova2, Michaela Piesova2
,
3,
Mojmír Mach2and Michal Zeman1
1Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava,
Slovakia; 2Centre of Experimental Medicine SAS, Institute of Experimental Pharmacology and Toxicology, Slovak
Academy of Sciences, Bratislava, Slovakia and 3Department of Pharmacology, Jessenius Faculty of Medicine,
Comenius University, Martin, Slovakia
Abstract
Prenatal hypoxia (PH) has negative consequences on the cardiovascular system in adulthood
and can affect the responses to additional insults later in life. We explored the effects of PH
imposed during embryonic day 20 (10.5% O
2
for 12 h) on circadian rhythms of systolic blood
pressure (BP) and heart rate (HR) in mature male rat offspring measured by telemetry. We
evaluated: (1) stability of BP and HR changes after PH; (2) circadian variability of BP and
HR after 2 and 5 weeks of exposure to artificial light at night (ALAN; 1–2 lx); and (3) response
of BP and HR to norepinephrine. PH increased BP in the dark (134 ±2 mmHg vs. control 127 ±
2 mmHg; p=0.05) and marginally in the light (125 ±1 mmHg vs. control 120 ±2 mmHg)
phase of the day but not HR. The effect of PH was highly repeatable between 21- and 27-week-
old PH male offspring. Two weeks of ALAN decreased the circadian variability of HR (p<0.05)
and BP more in control than PH rats. After 5 weeks of ALAN, the circadian variability of HR
and BP were damped compared to LD and did not differ between control and PH rats (p<0.05).
Responses of BP and HR to norepinephrine did not differ between control and PH rats. Hypoxia
at the end of the embryonic period increases BP and affects the functioning of the cardio-
vascular system in mature male offspring. ALAN in adulthood decreased the circadian variabil-
ity of cardiovascular parameters, more in control than PH rats.
Introduction
Cardiovascular diseases are of a multifactorial origin and can be programmed during prenatal
and perinatal development. Unfavourable conditions during prenatal development can have
negative consequences on the postnatal development of several organs and affect health in adult-
hood.1–3Prenatal hypoxia (PH) is one example of such a condition. During early stages, the
foetus can adapt to a reduced oxygen supply and increase blood distribution to critically impor-
tant organs, such as the brain and heart, while conversely reducing renal and gastrointestinal
perfusion.4In a poor intrauterine environment, the foetus develops long-lasting adaptations in
cardiovascular and endocrine functions.5If PH is present for a prolonged time and during criti-
cal periods of development, it can significantly affect the function of the vasculature, heart and
kidney, as well as several local6and central regulatory mechanisms.7
The timing of critical periods, which determine changes in sensitivity of organs to negative
stimuli, can differ among stimuli. However, the final days of pregnancy are particularly impor-
tant.8,9In our previous study, we found increased blood pressure (BP) and activation of the sym-
pathetic nervous system in adult male rats exposed prenatally to two 4-h periods of 10.5% of
oxygen on prenatal days 19 and 20.8PH can contribute to the development of hypertension and
higher susceptibility of the cardiovascular system to different environmental conditions, which
occur later in development or in adulthood.10,11
After birth, organisms are exposed to various environmental conditions, including regular
light (L) and dark (D) cycles. Rotation of the light/dark regimen is an important synchronisation
factor for central circadian oscillator localised in the suprachiasmatic nucleus of the hypothala-
mus. These clocks generate circadian rhythms of behavioural and physiological processes,
including the daily variability of BP and heart rate (HR).12,13 Circadian clock outputs are trans-
mitted via the endocrine and autonomic nervous system to the rest of body and entrain their
functions to the actual environmental LD cycle.14 Circadian clocks allow organisms to predict
regular changes during the 24-h cycle and help to cope more efficiently with stressors.15,16
Disruption of circadian rhythms can be induced by several environmental variables, including
artificial light at night (ALAN). Low ALAN levels (<10 lx) can disturb the circadian control of
different physiological processes, including the cardiovascular system in men.17 Moreover, low
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ALAN levels (1–2 lx) differentially affect the circadian control of
BP and HR in normotensive rats18 in comparison with spontane-
ously hypertensive rats,19 which have an activated sympathetic
nervous system.
PH increases BP and the activity of the sympathetic nervous
system, through which central biological clock outputs are medi-
ated and can be disturbed by ALAN. Therefore, in our present
study, we explored the effects of ALAN on circadian rhythms in
HR and BP in male offspring exposed to PH. We evaluated: (1)
stability of BP and HR changes after PH; (2) circadian variability
of BP and HR after 2 and 5 weeks of exposure to ALAN (1–2 lx);
and (3) response of BP and HR to norepinephrine in PH offspring.
Materials and methods
Animals
In our study, we examined mature male Wistar rats from nullipa-
rous female Wistar/DV rats (n=16). We induced PH on prenatal
day 20 by 12-h exposure of pregnant females (n=8) to 10.5% oxy-
gen in nitrogen. After the hypoxic insult, mothers were returned to
their home cages. Control pregnant females (n=8) were placed in
the hypoxic chamber on day 20 of gestation for 12 h without induc-
ing hypoxia. Animals were allowed to spontaneously deliver
offspring and pups were assigned to the groups after weaning
(21 days postpartum) using a single pup per litter to minimise
genetic bias as previously described.8,20 We maintained animals
individually in plastic cages with food and water available ad libi-
tum. The room temperature (21°C ±2°C), humidity (55% ±10%),
and regular 12-h L (150 lx):12-h D (0 lx) conditions were automati-
cally controlled. The experiment was approved by the Ethical
Committee for the Care and Use of Laboratory Animals at the
Comenius University in Bratislava, Slovak Republic and the
State Veterinary Authority of Slovak Republic.
Experimental design
Using telemetry, we evaluated daily rhythms of systolic BP and HR
in adult, 21- and 27-week-old PH (n=7, 370 ±8 g) or control
(n=6, 384 ±8 g) male offspring. During this period, rats were
exposed to regular 12L:12D conditions (Fig. 1). In 28–32-week-
old control and PH rats, we determined the response of daily
rhythms of BP and HR to ALAN: 12-h L (150 lx) and 12-h of
ALAN phases (dim D; 1–2 lx). We evaluated the consequences
of ALAN on circadian rhythms of BP and HR via telemetry after
2 and 5 weeks of ALAN exposure (Fig. 1). In 34-week-old rats, we
administered norepinephrine and analysed BP and HR response in
the control and PH group (Fig. 1).
Telemetry
We continuously measured BP and HR via telemetry (HD-S10;
Data Sciences International, MN, USA). We applied telemetry
transmitters to the abdominal aorta.8,18 After implantation, we
treated rats with tramadol (15 mg/kg; SC; Tramal, Stada, Bad
Vilbel, Germany) and placed them in a heated room. We allowed
the animals to recover for 2 weeks after surgery.
Norepinephrine administration
Norepinephrine (200 μg/kg; SC; arterenol bitartrate hydrate;
Calbiochem, Germany) was administered subcutaneously 3 h
beforethelightswereturnedoffand3hbeforethelightswere
turned on as we did in our previous experiments. Consequences
of norepinephrine and vehicle on BP and HR we analysed pre-
viously15 and therefore this procedure was not repeated in this
experiment. During the dark phase, norepinephrine was admin-
isteredunderredlightandtheprocedurelastedmaximum
1min.
Data analysis
We evaluated systolic BP and HR data as 12-h averages separately
for the L and D or dim D. We analysed 24-h variability as the differ-
ence (delta) between the L and D or dim D. Due to data normal-
isation, we expressed delta in % (in relation to LD week). We used
Chronos-Fit software to analyse parameters of circadian rhythm
(%rhythm, amplitude, acrophase and mesor) of BP and HR.21 %
rhythm is a chronobiological term for the coefficient of determi-
nation, that is, the squared coefficient of correlation times 100
(%rhythm =r2·100). It represents the percentage of variation in
the data that is explained by the fitted model. The amplitude is half
the range of oscillation of the wave. The acrophase is the peak time
of the cosine wave fitted to the data. The mesor is the rhythmically
adjusted mean as the mean level of rhythm calculated by cosinor
method.21
We expressed systolic BP and HR responses to norepinephrine
as the difference between the stimulated and basal values. We
defined the basal values separately for each rat as the value from
the 2-h segment before norepinephrine administration. We calcu-
lated the area under the curve from a 90-min norepinephrine
response.
We tested the normality of data distribution with the Shapiro–
Wilk test and subsequently analysed the data with two-tailed het-
eroscedastic Student’st-test (parameters of the circadian
rhythms). Stability of the PH model (Fig. 2) and the response of
BP and HR to norepinephrine (Fig. 3) was evaluated by two-
way analysis of variance (ANOVA) with repeated measures (fac-
tors: group, LD phase) followed by Tukey’s test. Exposure of rats
to ALAN (Fig. 4) was evaluated by two-way ANOVA with repeated
measures (factors: week, LD phase) followed by Tukey’s test. BP
and HR delta response to ALAN exposure was evaluated by
one-way repeated measures ANOVA (factor:week) followed by
Tukey’s test. Differences were considered statistically significant
at p<0.05. Statistical evaluations were performed using the stat-
istical package R, version 3.6.3 (R Foundation for Statistical
Computing, Vienna, Austria). Data are presented and visualised
as the arithmetic mean ±standard error of the mean (SEM;
Figs. 4a–f, 3a and b; Excel Office 365, Microsoft, Redmond,
USA) or as box plots with individual data points (Figs. 2,4g–j,
3c–f; R; package: ggplot2). The box representing the range from
the first to third quartiles; the band near the middle of the box
is the median, and the lines above and below the box indicate
the locations of the minimum and maximum value.
Results
Stability of the PH model
Blood pressure
In 21-week-old males, BP was significantly higher in PH compared
to control rats (134 ±2 mmHg vs. 127 ±2 mmHg; p=0.0504) dur-
ing the D phase. During the L phase, BP was marginally higher in
PH compared to control rats (125 ±1 mmHg; 120 ±2 mmHg;
p=0.0849). This pattern of BP was also preserved after 6 weeks
(Fig. 2). As expected, in both PH (p˂0.001) and control (p˂
0.01) rats, BP was higher during the D compared to the L phase.
588 H. Sutovska et al.
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PH did not affect parameters of the circadian rhythm of BP
(%rhythm, acrophase, amplitude, and mesor; Table 1).
Heart rate
In 21-week-old males, PH did not affect HR. We did not observe
differences between control and PH males (Fig. 2). In both PH
(p˂0.001) and control (p˂0.001) rats, HR was significantly higher
during the D compared to the L phase of the day. PH did not affect
the parameters of the circadian rhythm of HR (Table 2).
Exposure of PH male offspring to ALAN
Blood pressure
In control rats, BP was affected by both LD phase (p<0.001)
and ALAN (p=0.035; Fig. 4g).Delta,24-hvariability,was
affected by ALAN in control (p=0.033; Fig. 4g), but not in
PH (p=0.227; Fig. 4i) rats. In control rats, the difference
between L and dim D decreased significantly after 2 weeks of
ALAN (p=0.021; −60.5% ±11.8%) and was recovered after
5 weeks of ALAN (−16.7% ±24.8%; p=0.667) compared to
control LD conditions (Fig. 4g). In both control and PH rats,
ALAN did not affect BP during the L phase of the day
(Fig. 4g, i).
After 2 weeks of ALAN, the circadian rhythm of BP was dis-
rupted in control rats: only two of six rats exhibited significant
24-h variability. After 5 weeks of ALAN, the circadian rhythm
of BP was restored in five of six rats; however, %rhythm was still
significantly lower (p=0.029) compared to the LD regimen. In PH
rats, the circadian rhythm was disrupted after 5 weeks of ALAN;
%rhythm was decreased (p=0.042; Table 1). As demonstrated
with the actograms (Fig. 5), daily rhythmicity was still present
for all recorded parameters after 2 and 5 weeks of ALAN in control
and PH males.
Heart rate
In both control (Fig. 4h) and PH (Fig. 4j) rats, HR was affected by
LD phase and ALAN.
The LD difference decreased by 26.4% ±7.8% in control
(p=0.086) and by 15.8% ±3.8% in PH (p=0.049) rats after
Fig. 2. Effect of prenatal hypoxia on blood pressure and
heart rate in mature male offspring. *p<0.05 Data are
visualised as box plots with individual data points.
Fig. 1. Experimental design. LD, regular 12-h light:12-h dark regimen; PH, prenatal hypoxia; ALAN, artificial light (1–2 lx) during the dark phase of the day; NE, norepinephrine.
Journal of Developmental Origins of Health and Disease 589
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2 weeks of ALAN. After 5 weeks of ALAN, the LD difference was
restored in control (p=0.721 vs. LD regimen, Fig. 4h) rats, while in
PH rats it was continuously decreased (−28.7% ±4.3%; p<0.001,
Fig. 4j) compared to the LD regimen.
Two weeks of ALAN suppressed %rhythm (p=0.011), ampli-
tude (p=0.004), and mesor (p=0.008) in control but not PH
males. After 5 weeks of ALAN, the %rhythm was significantly
decreased in control (p=0.004) and PH (p=0.016) rats (Table 2).
Response to norepinephrine
Response to norepinephrine administration was significantly
higher during the L compared to the D phase of the day in both BP
(p=0.003) and HR (p<0.001; Fig. 3). PH and control males did
not differ in the BP and HR response to norepinephrine (Fig. 3).
Discussion
Hypoxic conditions during embryonic life can contribute to
hypertension in adulthood and change the response of offspring
to environmental challenges. In the current study, we found that:
(1) half-day hypoxia on prenatal day 20 consistently increased BP
in mature (21 and 27 weeks old) male offspring; (2) PH rats were
less sensitive to ALAN compared to control rats after 2-week
exposure, but after 5-week exposure, the circadian control of
HR and BP variability was equally suppressed in both groups
in comparison with LD; and (3) BP and HR responses to norepi-
nephrine administration were not different between PH and con-
trol rats.
PH can affect the development of the foetus and control mech-
anisms that act postnatally.7The extent of functional changes
caused by negative prenatal conditions depends on their intensity
and time when they act.22 Our results showed that 12-h hypoxia
during prenatal day 20 resulted in higher BP but not HR compared
to control adult male rats. It is necessary to mention that changes in
BP and HR caused by 12-h prenatal hypoxia were stable and did
not differ between 21- and 27-week-old rats. These results are con-
sistent with our previous data demonstrating that even shorter
(4 h) durations of hypoxic conditions during prenatal days 19
and 20 can increase BP in adulthood.8In contrast, the same level
of hypoxia (10.5%) applied in the middle of the embryonic devel-
opment (days 8–14) did not increase BP in adult male rats (our
unpublished data). PH can affect different regulatory areas in
the brain and alter the expression of adrenergic receptors in the
heart and arteries.23–25 These changes can lead to a modified func-
tion of the autonomic nervous system and increase sympathetic
nervous system activity.8Long-lasting PH can affect both the
central and peripheral control mechanisms mediated by transcrip-
tomic and epigenomic mechanisms.26 In our experiment, we
Fig. 3. (a) Blood pressureand (b) heart rate responseson norepinephrine administration. Responsesof (c) blood pressure and (d) heart rate on norepinephrine analysedas the area
under the curve (AUC).Maximal time in minutes of (e) blood pressure, and (f) heart rate responses on norepinephrine.*p<0.05, **p<0.01. Data are visualised as the arithmetic mean
±standard error of the mean (a, b) and normalised to the value before norepinephrine administration or as box plots with individual data points (c–f).
Notes: dashed grey line, prenatal hypoxia mature male offspring in the light phase of the day; dashed black line, prenatal hypoxia mature male offspringinthedarkphaseof
the day; grey line, control rats in the light phase; black line, control rats in the dark phase of the day; light grey box plots, light phase of the day; dark grey box plots, da rk phase
of the day.
590 H. Sutovska et al.
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Fig. 4. Effect of artificial light at night (ALAN) on blood pressure and heart rate in control and prenatal hypoxia affected rats. Original data from telemetry: (a) blood pressure and
(b) heart rate in 21- and 27-week-old (21 week, 27 week) rats during the LD regimen (L light phase 150 lx, D dark phase 0 lx). (c) Blood pressure and (d) heart rate in 29-week-old (29
week) rats during the second week of the ALAN regimen (A2). (e) Blood pressure and (f) heart rate in 32-week-old (32 week) rats during the fifth week of ALAN (A5). The dashed black
line indicates prenatal hypoxia mature male offspring, while the grey line represents control rats. Grey and white vertical bars represent the D and L phase, respectively. Data are
visualised as the arithmetic mean ±standard error of the mean. Mean values of (g) blood pressure and (h) heart rate and their differences between L and D phases of days in %
(delta) in control rats. Mean values of (i) blood pressure and (j) heart rate and their differences between L and D phases of days in % (delta) in prenatal hypoxia mature male
offspring. Data are visualised as box plots with individual data points. *p<0.05, ***p<0.001.
Journal of Developmental Origins of Health and Disease 591
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exposed animals to PH for 12 h, and even such short exposure can
change endothelial mechanisms responsible for higher BP in adult
rats.27 PH leads to endothelial dysfunction in systemic resistance
arteries and affects the acute regulation of BP,5,28 while chronic
regulation of BP is mediated by the kidney. Prenatal adverse con-
dition reduces foetal kidney growth and reduces the number of
nephrons5and glomeruli,29 an alteration that is often associated
with later development of hypertension.5It leads in the kidney
to upregulation of renin–angiotensin–aldosterone system.28
While daily rhythms of recorded parameters persisted after
ALAN exposure, the treatment suppressed circadian variability
(amplitude, %rhythm) of BP and HR in both PH and control rats.
We analysed the stability of circadian rhythms by Cosinor analysis
and as the difference between the L and D or dim D phase. In the
control group, ALAN suppressed considerably 24-h variability of
BP and HR after 2 weeks of exposure. After 5 weeks of ALAN, 24 h
variability of BP and HR was restored. We identified a different
pattern in the PH group: we did not find such pronounced sup-
pression of circadian variability of BP and HR after 2 weeks of
ALAN as in the control group. However, the light–dark variability
of both parameters continuously decreased after 5 weeks of ALAN
in PH rats, and there was no difference between the groups at that
time. These results are in line with our previous study,18 in which
ALAN of the same intensity suppressed circadian variability of BP
and HR in rats together with changes of spontaneous baroreflex
sensitivity. On the other hand, in spontaneously hypertensive
rats,19 the consequences of ALAN resembled those in PH rats
found in this study. These data show that even low-intensity
ALAN can act as a mild circadian disruptor and, consequently,
interfere with circadian rhythms in cardiovascular parameters. It
is necessary to mention that disruption of 24-h oscillations of
cardiovascular parameters, especially BP, is associated with cardio-
vascular risk in humans and is used as a prognostic factor.12 Our
data suggest that PH can change regulatory mechanisms that con-
trol the cardiovascular system and responses to environmental
stimuli. The nature of these changes is still unknown, but the
autonomic nervous system can be involved because PH and spon-
taneously hypertensive rats have up-regulated activity of the sym-
pathetic nervous system.8,30
Light is received by the retina and intrinsically photosensitive
ganglion cells transmit the information to the central circadian
oscillator localised in the suprachiasmatic nucleus of the hypo-
thalamus. From there, the entrained rhythmic signals are passed
to the paraventricular nucleus (PVN) of the hypothalamus, which
controls the endocrine and sympathetic system.31 Among the hor-
monal signals, the circadian rhythm of melatonin synthesis in the
pineal gland can be of primary importance because it represents a
direct output of the central circadian clocks and melatonin has a
pleiotropic action. The circadian rhythm of plasma melatonin con-
centrations was eliminated in our previous study by the same
low light illuminance18 as we applied in the present experiment.
Melatonin can influence the brain structures involved in the BP
control and reactivity of peripheral vessels.32
In addition to its role in the control of the endocrine system, the
PVN is involved in the regulation of the autonomic nervous sys-
tem.33 Morphological and electrophysiological studies have shown
that PVN is reciprocally connected to regions of the brain that are
involved in cardiovascular regulation. Importantly, the PVN pro-
jects to both the intermediolateral cell column of the spinal cord
and the rostral ventrolateral medulla, regions critical in the control
of the sympathetic nervous system and the cardiovascular
system.34
Table 1. Parameters (mean ±standard error of the mean [SEM]) of the circadian rhythm in blood pressure after 2 and 5 weeks of artificial light at night (ALAN)
exposure
LD, control week ALAN, week 2 ALAN, week 5
Control
n=6
Prenatal hypoxia
n=7
Control
n=6
Prenatal hypoxia
n=7
Control
n=6
Prenatal hypoxia
n=7
Nr rhythmic animals 5/6 7/7 2/6 7/7 5/6 7/7
%rhythm 21.11 ±2.07 21.35 ±2.21 5.56 ±1.47** 16.13 ±2.97*** 12.32 ±1.74* 13.87 ±2.21*
Acrophase 18.30 ±0.68 17.33 ±0.26 15.47 ±3.91 17.81 ±0.44 18.83 ±0.44 18.13 ±0.29
Amplitude 4.30 ±0.48 6.00 ±0.60 3.16 ±0.33 4.91 ±0.40 2.91 ±0.30 4.28 ±0.29
Mesor 126 ±3 129 ±1 123 ±3 128 ±1 125 ±3 129 ±2
*p<0.05 vs. LD; **p<0.01 vs. LD; ***p<0.05 control vs. prenatal hypoxia in the same week.
Table 2. Parameters (mean ±standard error of the mean [SEM]) of the circadian rhythm in heart rate after 2 and 5 weeks of artificial light at night (ALAN) exposure
LD, control week ALAN, week 2 ALAN, week 5
Control
n=6
Prenatal hypoxia
n=7
Control
n=6
Prenatal hypoxia
n=7
Control
n=6
Prenatal hypoxia
n=7
Nr rhythmic animals 6/6 7/7 6/6 7/7 6/6 7/7
%rhythm 37.55 ±3.28 35.36 ±3.22 21.28 ±2.61* 31.79 ±3.44*** 27.67 ±2.73* 24.77 ±2.15**
Acrophase 17.10 ±0.25 16.73 ±0.17 17.42 ±0.25 17.31 ±0.31* 17.75 ±0.21 17.53 ±0.22 *
Amplitude 37.99 ±3.46 35.10 ±5.30 23.53 ±3.34** 33.36 ±2.13*** 32.54 ±2.93* 25.44 ±1.97
Mesor 352 ±5 311 ±34 342 ±5** 340 ±6 335 ±6** 324 ±4
*p<0.05 vs. LD; **p<0.01 vs. LD; ***p<0.05 control vs. prenatal hypoxia in the same week.
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Gestational intermittent hypoxia,35 as well as perinatal hypoxia
(E19 to PD14),36 can upregulate sympathetic outflow to the
heart and vessels. Moreover, hypoxia increases expression of
ɑ
1
-adrenergic receptors in arteries,23 but not β
1
-adrenergic
receptors in the heart24 and chronic PH causes postnatal desen-
sitization of β-adrenoceptors in the heart.37 Therefore, PH in our
study could increase BP but not HR. The centrally increased sym-
pathetic activity can at least partially explain the increased resistance
of PH animals to ALAN. We hypothesise that the activated sympa-
thetic nervous system in PH rats can stabilise the outflow to the ros-
tral ventrolateral medulla and protect against disturbing effects of
ALAN after 2 weeks of ALAN in comparison with control animals.
In the last part of our study, we tested the significance of ɑ-
adrenergic signalling on vessels in rats by evaluating the response
of BP to norepinephrine administration. The response to norepi-
nephrine was phase-dependent; both control and PH groups
showed higher response during the L in comparison with the D
phase of the day. These data are in line with our previous stud-
ies.8,15 The absence of differences in the BP response to norepi-
nephrine administration between PH and control rats does not
exclude the participation of the sympathetic nervous system in
their different response to ALAN at the central level because
peripherally administered norepinephrine is unable to penetrate
the blood-brain barrier.38 Furthermore, the expression of adrener-
gic receptors in the heart and blood vessels23–25 can be different and
should be further studied.
Conclusions
Prenatal hypoxia increased BP in mature male rats and permanently
affected regulatory mechanisms controlling the cardiovascular
system. Daily rhythms of recorded parameters were dumped after
ALAN exposure in both groups and the response of BP to ALAN
was more pronounced in the control compared to PH rats after
2 weeks of exposure. The higher resistance of PH animals to
ALAN can be explained at least partially by centrallyincreased sym-
pathetic activity and supressed melatonin rhythmicity.
Acknowledgements. We would like to thank Proof Reading Servis.com, the
UK for the professionally proofread of the manuscript.
Financial Support. The study was supported by the Slovak Research and
Development Agency (APVV-17-0178) and the Scientific Grant Agency of
the Ministry of Education of the Slovak Republic (VEGA 1/0492/19, VEGA
2/0154/20).
Conflicts of Interest. The authors declare that there is no conflict of interest.
Ethical Standards. The experiment was approved by the Ethical Committee
for the Care and Use of Laboratory Animals at the Comenius University in
Bratislava, Slovak Republic and the StateVeterinary Authorityof Slovak Republic.
References
1. Giussani DA, Davidge ST. Developmental programming of cardiovascular
disease by prenatal hypoxia. J Dev Orig Health Dis. 2013; 4, 328–337.
2. Kumar P, Morton JS, Shah A, et al. Intrauterine exposure to chronic hypo-
xia in the rat leads to progressive diastolic function and increased aortic
stiffness from early postnatal developmental stages. Physiol Rep. 2020;
8, e14327.
3. Andraweera PH, Gatford KL, Care AS, et al. Mechanisms linking exposure
to preeclampsia in utero and the risk for cardiovascular disease. J Dev Orig
Health Dis. 2020; 1–8.
Fig. 5. Representative individual actograms of heart rate (HR), systolic blood pressure (BP), locomotor activity (LA) and body temperature (BT) in freely moving control and
mature offspring exposed to prenatal hypoxia during regular 12-h light:12-h dark (C) and second (A2) and fifth (A5) week of the artificial light at night exposure. Actograms were
made from raw data by Chronos-Fit. Data for each week is from a 3-day measurement.
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4. Giussani DA, Camm EJ, Niu Y, et al. Developmental programming of
cardiovascular dysfunction by prenatal hypoxia and oxidative stress.
PLoS ONE. 2012; 7, e31017.
5. Verschuren MTC, Morton JS, Abdalvand A, et al. The effect of hypoxia-
induced intrauterine growth restriction on renal artery function. J Dev
Orig Health Dis. 2012; 3, 333–341.
6. Alma LJ, De Groot CJM, De Menezes RX, et al. Endothelial
dysfunction as a long-term effect of late onset hypertensive pregnancy
disorders: high BMI is key. Eur J Obstet Gynecol Reprod Biol. 2018; 225,
62–69.
7. Tain Y-L, Huang L-T, Hsu C-N. Developmental programming of adult dis-
ease: reprogramming by melatonin? Int J Mol Sci. 2017; 18, 426.
8. Svitok P, Molcan L, Stebelova K, et al. Prenatal hypoxia in rats increased
blood pressure and sympathetic drive of the adult offspring. Hypertens
Res. 2016; 39, 501–505.
9. Van den Bergh BR, van den Heuvel MI, Lahti M, et al. Prenatal develop-
mental origins of behavior and mental health: the influence of maternal
stress in pregnancy. Neurosci Biobehav Rev. Epub ahead of print 28 July
2017. doi: 10.1016/j.neubiorev.2017.07.003.
10. Shah A, Matsumura N, Quon A, et al. Cardiovascular susceptibility to
in vivo ischemic myocardial injury in male and female rat offspring exposed
to prenatal hypoxia. Clin Sci. 2017; 131, 2303–2317.
11. Zeman M, Okuliarova M. Sex-specific cardiovascular susceptibility to
ischaemic myocardial injury following exposure to prenatal hypoxia.
Clin Sci. 2017; 131, 2791–2794.
12. Smolensky MH, Hermida RC, Portaluppi F. Circadian mechanisms of
24-hour blood pressure regulation and patterning. Sleep Med Rev. 2017;
33, 4–16.
13. Black N, D’Souza A, Wang Y, et al. Circadian rhythm of cardiac electro-
physiology, arrhythmogenesis, and the underlying mechanisms. Heart
Rhythm. 2019; 16, 298–307.
14. Coomans CP, Ramkisoensing A, Meijer JH. The suprachiasmatic nuclei as a
seasonal clock. Front Neuroendocrinol. 2015; 37, 29–42.
15. Molcan L, Vesela A, Zeman M. Repeated phase shifts in the lighting regi-
men change the blood pressure response to norepinephrine stimulation in
rats. Physiol Res. 2014; 63, 567–575.
16. Chellappa SL, Vujovic N, Williams JS, Scheer FA. Impact of circadian dis-
ruption on cardiovascular function and disease.Trends Endocrinol Metab.
2019; 30, 767–779.
17. Obayashi K, Saeki K, Iwamoto J, Ikada Y, Kurumatani N. Association
between light exposure at night and nighttime blood pressure in the elderly
independent of nocturnal urinary melatonin excretion. Chronobiol Int.
2014; 31, 779–786.
18. Molcan L, Sutovska H, Okuliarova M, et al. Dim light at night attenuates
circadian rhythms in the cardiovascular system and suppresses melatonin
in rats. Life Sci. 2019; 231, 116568.
19. Rumanova VS, Okuliarova M, Molcan L, Sutovska H, Zeman M.
Consequences of low-intensity light at night on cardiovascular and meta-
bolic parameters in spontaneously hypertensive rats. Can J Physiol
Pharmacol. 2019; 97, 863–871.
20. Ujhazy E, Dubovicky M, Navarova J, et al. Subchronic perinatal asphyxia
in rats: embryo–foetal assessment of a new model of oxidative stress
during critical period of development. Food Chem Toxicol. 2013; 61,
233–239.
21. Zuther P, Gorbey S, Lemmer B. Chronos-Fit 1.06. Chronos-Fit. 2009.
http://www.ma.uni-heidelberg.de/inst/phar/lehre/chrono.html.
22. Schulz LC. The Dutch Hunger Winter and the developmental origins of
health and disease. Proc Natl Acad Sci. 2010; 107, 16757–16758.
23. Eckhart AD, Zhu Z, Arendshorst WJ, Faber JE. Oxygen modulates alpha
1B-adrenergic receptor gene expression by arterial but not venous vas-
cular smooth muscle. Am J Physiol-Heart Circ Physiol. 1996; 271,
H1599–H1608.
24. Hutchinson DS, Brew N, Vu T, et al. Effects of hypoxia-ischemia and ino-
tropes on expression of cardiac adrenoceptors in the preterm fetal sheep.
J Appl Physiol. 2018; 125, 1368–1377.
25. Moretta D, Papamatheakis DG, Morris D, et al. Long-term high altitude
hypoxia and alpha adrenoceptor-dependent pulmonary arterial contrac-
tions in fetal and adult sheep. Front Physiol. 2019; 10, 1032.
26. Chen X, Zhang L, Wang C. Prenatal hypoxia-induced epigenomic and tran-
scriptomic reprogramming in rat fetal and adult offspring hearts. Sci Data.
2019; 6, 1–8.
27. Chen X, Qi L, Fan X, et al. Prenatal hypoxia affected endothelium-depen-
dent vasodilation in mesenteric arteries of aged offspring via increased oxi-
dative stress. Hypertens Res. 2019; 42, 863–875.
28. Walton SL, Bielefeldt-Ohmann H, Singh RR, et al. Prenatal hypoxia
leads to hypertension, renal renin-angiotensin system activation and
exacerbates salt-induced pathology in a sex-specific manner. Sci Rep.
2017; 7, 1–13.
29. Svitok P, Husková Z, Červenková L, et al. The exaggerated salt-sensitive
response in hypertensive transgenic rats (TGR mRen-2) fostered by a nor-
motensive female. Hypertens Res. 2019; 42, 459–468.
30. Yang K, Wang Y, Ding Y, et al. Valsartan chronotherapy reverts the non-
dipper pattern and improves blood pressure control through mediation of
circadian rhythms of the renin-angiotensin system in spontaneous hyper-
tension rats. Chronobiol Int. 2019; 36, 1058–1071.
31. Thosar SS, Butler MP, Shea SA. Role of the circadian system in cardio-
vascular disease. J Clin Invest. 2018; 128, 2157–2167.
32. Nishi EE, Almeida VR, Amaral FG, et al. Melatonin attenuates renal
sympathetic overactivity and reactive oxygen species in the brain in
neurogenic hypertension. Hypertens Res Off J Jpn Soc Hypertens. 2019;
42, 1683–1691.
33. Coote JH. A role for the paraventricular nucleus of the hypothalamus
in the autonomic control of heart and kidney. Exp Physiol. 2005; 90,
169–173.
34. Pyner S, Coote JH. Identification of branching paraventricular neurons of
the hypothalamus that project to the rostroventrolateral medulla and spinal
cord. Neuroscience. 2000; 100, 549–556.
35. Fan J-M, Wang X, Hao K, et al. Upregulation of PVN CRHR1 by gestational
intermittent hypoxia selectively triggers a male-specific anxiogenic effect in
rat offspring. Horm Behav. 2013; 63, 25–31.
36. Raff H, Jacobson L,Cullinan WE. Augmented hypothalamic corticotrophin-
releasinghormone mRNA and corticosterone responses to stress in adult rats
exposed to perinatal hypoxia. J Neuroendocrinol. 2007; 19, 907–912.
37. Lindgren I, Altimiras J. Chronic prenatal hypoxia sensitizes β-adrenocep-
tors in the embryonic heart but causes postnatal desensitization. Am J
Physiol-Regul Integr Comp Physiol. 2009; 297, R258–R264.
38. Kostrzewa RM. The blood-brain barrier for catecholamines —Revisited.
Neurotox Res. 2007; 11, 261–271.
594 H. Sutovska et al.
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