Adrenal Function in Cockerels1

Abstract

Corticosterone concentration, as determined by a validated fluorometric method, in adrenal vein effluent plasma of adeno-hypophysectomized cockerels was partially maintained, at 37% of control. Similar results were obtained from incubation of adrenal slices of both intact and adenohypophysectomized cockerels in vitro. Steroid concentration in adrenal vein plasma decreased sharply in both groups of cockerels following Metopirone treatment. Arginine vasotocin had no adrenocorticotrophic effect upon either group. Corticosterone concentration increased after 1 hr. of surgical stress in adrenal plasma of adenohypophysectomized cockerels but decreased after 4 hr. of surgical stress. The adrenals of intact cockerels responded positively in both cases. Treatment with dexamethasone phosphate eliminated corticosterone from adrenal vein plasma of both groups of cockerels, but failed to inhibit corticosterone synthesis from endogenous precursors at 3 different dose levels in incubated adrenal slices of intact cockerels. These results suggest that adrenal function in adrenohypo-physectomized cockerels is not autonomous, as has been commonly thought, but is supported by an extrahypophyseal adrenocorticotrophin; and also present unique proof that, at last in cockerels, the site of adrenocortical hormone feedback is not at the pituitary level.