title: Developmental aspects of pituitary and adrenal responses to arterial hypotension in neonatal, weanling, and adult sheep.
abstract: We have studied neuroendocrine and heart rate responses to arterial hypotension in unanesthetized, chronically cannulated neonatal (less than 10 days old), weanling (3- to 4-wk-old), and adult sheep. Nitroprusside-induced arterial hypotension in the absence of hypovolemia promptly increased plasma ACTH, vasopressin (AVP), and cortisol levels in all three groups. The integrated adenohypophyseal and neurohypophyseal responses to a standard hypotensive stimulus were similar at the three ages, suggesting that the functional development of the systems subserving these responses is complete by the immediate postnatal period. The integrated cortisol/ACTH ratio was greatest in the youngest animals, suggesting that enhanced adrenal responsiveness to ACTH exists in neonatal as well as in late-gestation fetal lambs. The reflex tachycardia accompanying the arterial hypotension in the weanling and adult sheep was absent in the neonates.
mesh_terms: D000311:Adrenal Glands / Q000254:growth & development / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects; D006854:Hydrocortisone / Q000097:blood*; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology*; D009599:Nitroprusside / Q000494:pharmacology; D010902:Pituitary Gland / Q000254:growth & development / Q000378:metabolism*; D012756:Sheep
chemical_list: D009599:Nitroprusside; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone