Ovine fetal hormonal and hypothalamic neuroendocrine responses to maternal water deprivation at late gestation

Abstract

Angiotensin II (Ang II), aldosterone, and arginine-vasopressin (AVP) are three major neuropeptides or hormones that are important in the control of body fluid regulation. Dehydration during pregnancy induces alterations in maternal-fetal fluid homeostasis. It is still not clear about effects and mechanisms of maternal water deprivation on fetal neuroendocrine and hormonal responses. The present study deprived water from pregnant sheep at near-term for 24 h and 48 h, and determined maternal and fetal blood osmolality and sodium levels before and immediately after water deprivation. Fetal renal excretion and plasma hormones were measured. Fetal forebrain was analyzed for cellular activation marked with Fos and Fos-B. The results showed that maternal and fetal blood osmolality and sodium were increased by water deprivation. Maternal and fetal Ang II, aldosterone, and AVP levels were elevated by 24-h and 48-h water deprivation, while fetal plasma Ang I levels were increased only under the condition of 48-h water deprivation. Intensive Fos and Fos-B expression was detected in the median preoptic nuclei and paraventricular nuclei in the fetal brain following exposure to maternal water deprivation. Double labeling demonstrated that many Fos-positive cells were AVP-containing neurons in the fetal paraventricular nucleus. Together, the results suggest that neuroendocrine and hormonal regulatory mechanisms play a role in the control of body fluid homeostasis, and relatively matured and functional at the last third of gestation, as well as the fetal hypothalamus is functional in the control of the neuropeptide in response to maternal dehydration.

New conception for the development of hypertension in preeclampsia

“…Pregnant sheep (gestational age, 130-135 days; term, 147±3 days) were housed in a light-controlled room with standard food and water before general anesthesia. Anesthesia was initiated by ketamine hydrochloride (20 mg/kg, intramuscularly), and general anesthesia was maintained with 1 l/min oxygen and 1-2% isoflurane as described [29]. Under anesthesia, cesarean section was performed, umbilical vein and artery, placental vessels and non-placental vessels such as carotid artery, and renal artery were collected from fetal sheep.…”

Ovine uterine space restriction causes dysregulation of the renin–angiotensin system in fetal kidneys^{<xref ref-type="fn" rid="afn1">†</xref>}

“…Likewise, angiotensin receptors were directly correlated to osmolarity, but both these relationships were dominated by USR fetuses with the highest osmolarity. Fetal osmolarity is normally controlled by the placenta, not the fetus [23], and the relationship was dominated by fetuses whose plasma osmolarity was higher than levels reported in normal late gestation fetuses [24,25]. In this model, we previously found a fluid shift away from fetus toward the placenta in USR fetuses and perhaps the fall in plasma renin activity in USR at GD130 may reflect this shift.…”

Causes of length of conotruncus of embryonic mouse heart at normal condition and under the maternal dehydration

“…При этом обезвоживание организма матери разной степени тяжести сопровождает ряд заболеваний первого триместра беременности (гестозы, экстрагенитальная патология). Сложность гистогенетических перестроек конусно-стволового отдела эмбрионального сердца на пути формирования магистрального сосудистого поля в достаточно короткий период времени обусловливает выбор именно этого отдела сердца для предпочтительной экспериментальной модели [5,12].…”