Growth hormone and ACTH secretion: evidence for an inverse relationship in rats.

Abstract

Plasma growth hormone (GH), corticosterone and blood glucose concentrations were measured in rats after the following treatment: (A) noise and vibration stress, ether inhalation, cold exposure, insulin hypoglycemia and administration of pentylenetetrazol, amphetamine or 2-Ddeoxyglucose; (B) gentling, or administration of pentobarbital or morphine. All the procedures under (A) caused a characteristic rise of plasma corticosterone and a fall of plasma GH when compared to rats sacrificed immediately after IP injection of saline. In the experiments under (B), it was shown that gentled-unstressed rats have significantly lower corticosterone and higher GH in plasma than gentled-stressed rats, and that pentobarbital and morphine enhanced GH secretion. Simultaneous increases of plasma corticosterone and GH were observed only after morphine. Morphine stimulation of GH release was blocked by insulin hypoglycemia but not by pretreatment with dexamethasone. On the other hand, dexamethasone blocked the acute stimulant...