Fetal endocrine responses to prolonged reduced uterine blood flow are altered following bilateral sectioning of the carotid sinus and vagus nerves

Stein, P.; White, Susan; Homan, Jacobus; Fraher, L. J.; Mcgarrigle, H. H. G.; Hanson, MA; Bocking, Alan D.

doi:10.1677/joe.0.1570149

Cited by 7 publications

(3 citation statements)

References 29 publications

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“…Exposure to hypoxia for several days has been demonstrated to result in increased levels of key enzymes for catecholamine production [17]. High plasma catecholamine levels [41] and maintenance of the redistribution of the cardiac output [22] have been observed during chronic hypoxia in the fetus.…”

Section: Introductionmentioning

confidence: 99%

Chronic moderate hypoxia during in ovo development alters arterial reactivity in chickens

Ruijtenbeek¹,

Kessels²,

Janssen

et al. 2003

Pflugers Arch - Eur J Physiol

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We previously observed arterial sympathetic hyperinnervation and endothelial dysfunction in the chicken embryo after exposure to chronic hypoxia. We now investigate whether changes in arterial properties could also be observed at 14-15 weeks of life. Eggs of White Leghorn chicken were incubated under normoxic or moderately hypoxic (15% O2 from days 6-19 of a 21-day incubation) conditions. Experiments were performed at 14-15 weeks of life under standard conditions (Hm: males exposed to hypoxia; Hf: females exposed to hypoxia; Nm: males exposed to normoxia; Nf: females exposed to normoxia). Body weight at hatching and at 14-15 weeks was not affected by in ovo exposure to hypoxia. Mean arterial pressure and heart rate were not significantly altered by chronic in ovo hypoxia. However, isolated femoral arteries were more sensitive to electrical stimulation (frequency in Hz of half-maximal contraction, Hm: 1.62+/-0.33, Hf: 1.92+/-0.88, Nm: 2.49+/-0.49, Nf: 2.83+/-0.31) and pharmacological stimulation of peri-arterial sympathetic nerves (contraction in N/m in response to tyramine: Hm: 5.27+/-0.85, Hf: 4.10+/-0.9, Nm: 2.26+/-0.67, Nf: 3.65+/-0.51, p=0.07) after in ovo hypoxia. In side branches of the femoral artery, the effect of NO synthase blockade with L-NAME on contraction (in N/m) in response to high K+ (Hm: 0.35+/-0.91, Hf: 1.29+/-0.36, Nm: 2.88+/-0.19, Nf: 2.79+/-0.58) and on the sensitivity to acetylcholine (DeltapD2, H: 0.32+/-0.11, N: 0.62+/-0.05) was reduced after in ovo hypoxia. The present study shows that exposure to chronic moderate hypoxia during development affects the contractile and relaxing arterial responses of 14- to 15-week-old chickens. Although hypoxia did not lead to changes in blood pressure at this age, the observed effects on arterial sympathetic and endothelial function may represent early signs of future cardiovascular abnormalities.

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Section: Introductionmentioning

confidence: 99%

Chronic moderate hypoxia during in ovo development alters arterial reactivity in chickens

Ruijtenbeek¹,

Kessels²,

Janssen

et al. 2003

Pflugers Arch - Eur J Physiol

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“…Acute hypoxia (1,4,16), hypotension (26,32), and hemorrhage (25,34) all have profound stimulatory effects on the fetal hypothalamic-pituitary-adrenal axis (HPA). Short-term reductions in uterine blood flow also enhance cortisol secretion in the ovine fetus (3,27). Placental embolization to induce fetal hypoxia for up to 3 wk (20) has also been shown to result in elevated fetal ACTH and cortisol concentrations.…”

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confidence: 99%

Long-term hypoxia alters ovine fetal endocrine and physiological responses to hypotension

Adachi

Umezaki

Kaushal

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

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Exposure to long-term hypoxia (LTH) results in altered cortisol responses in the ovine fetus. The present study was designed to test the hypothesis that LTH alters adrenal responsiveness to fetal hypotension. Pregnant ewes were maintained at high altitude (3,820 meters) from day 30 of gestation. Normoxic control and LTH fetuses were catheterized on day 132 of gestation. In the LTH group, maternal Po(2) was maintained comparable to that observed at altitude ( approximately 60 mmHg) by nitrogen infusion through a tracheal catheter. On day 137, fetuses received a 5-h saline infusion followed by infusion of sodium nitroprusside to reduce fetal arterial pressure by 30-35% for 10 min. The study was repeated on day 139 of gestation with a continuous cortisol infusion (10 microg/min). Hypothalamic and pituitary tissues were collected from additional fetuses for assessment of glucocorticoid receptors. During the saline infusion in response to hypotension, plasma ACTH increased over preinfusion mean values in both groups (P < 0.05). Plasma cortisol concentrations increased in both groups concomitant with increased ACTH secretion. However, peak values in the LTH fetuses were significantly higher compared with controls (P < 0.05). During the cortisol infusion, the ACTH response was eliminated in both groups, with ACTH levels significantly lower in the LTH group (P < 0.05). Glucocorticoid receptor binding was not different between groups. These results demonstrate an enhanced cortisol response to hypotension in LTH fetuses that does not appear to be the result of an increase in negative feedback sensitivity of the hypothalamic-pituitary-adrenal axis.

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“…The mechanisms responsible for the adaptation to hypoxaemia are as yet unknown, but recent work indicates that the peripheral chemoreceptors are involved, as in their absence circulating levels of catecholamines are significantly lower than in intact fetuses (Stein et al 1997). Also, adrenocorticotrophic hormone (ACTH), cortisol and arginine vasopressin are markedly attenuated in denervated compared with intact fetuses in response to prolonged (6 h) hypoxaemia (Stein et al 1998). Altered levels of these hormones may have consequences for the cardiovascular development of the fetus (P. Hawkins, C. Crowe, H. G. McGarrigle, T. Saito, T. Ozaki, L. L. Stratford, D. E. Noakes & M. A. Hanson, personal communication) and neonate (Hawkins et al 1997).…”

Section: Various Methods By Which Chronic Hypoxaemia Has Been Producementioning

confidence: 99%

The effect of repeated acute hypoxaemia on fetal cardiovascular development in the sheep

Steyn

Hanson

1998

The Journal of Physiology

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1. Hypoxaemia during intrauterine life may be important in the development of cardiovascular diseases in later life. Thus it was the aim of this study to investigate the effect of repeated acute hypoxia on the cardiovascular development and growth of the fetus. 2. Fourteen fetal sheep (105-109 days gestational age) were instrumented with amniotic and vascular catheters, an electrocardiogram (ECG) electrode and a flow probe around the femoral artery. Seven animals were given repeated acute isocapnic hypoxaemia (Pa,Oµ reduced to ca. 13 mmHg) for 1 h every day for 14 days and they were compared to seven animals which remained normoxic throughout with respect to fetal mean arterial blood pressure (MAP), fetal heart rate (FHR), and fetal baro-and chemoreflexes. 3. No differences were found between the two groups of fetuses in FHR, MAP, baro-or chemoreflexes, femoral blood flow, femoral vascular resistance or fetal growth. 4. Repeated acute hypoxaemia of a moderate degree over a period of 2 weeks in late gestation does not affect cardiovascular development or growth in the fetal sheep.

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Fetal endocrine responses to prolonged reduced uterine blood flow are altered following bilateral sectioning of the carotid sinus and vagus nerves

Cited by 7 publications

References 29 publications

Chronic moderate hypoxia during in ovo development alters arterial reactivity in chickens

Chronic moderate hypoxia during in ovo development alters arterial reactivity in chickens

Long-term hypoxia alters ovine fetal endocrine and physiological responses to hypotension

The effect of repeated acute hypoxaemia on fetal cardiovascular development in the sheep

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