Nonsteroidal adrenal feedback demarcates two types of pathways to CRF-ACTH release

Abstract

The relationship between corticosterone (B) and the number of adrenal glands on stimulated ACTH levels was tested in rats. Rats were supplied throughout the experiment with various doses of B in the drinking fluid beginning 15-20 h before adrenal surgery. Bilateral, unilateral or sham adrenalectomy was followed on the 3rd day by the stimulus of ether vapor or ether and laparotomy with intestinal traction. Plasma ACTH levels 3 min after the stimuli were decreased by both the dose of B and the number of adrenals, although prestimulus ACTH and B levels were similar across groups. The decrease in ACTH after ether resulted from an interaction between the dose of B and the adrenal number; there was no interaction between the inhibitors after laparotomy with intestinal traction. In addition to B, some aspect of adrenal gland number or mass inhibits the ACTH response to stimuli. The adrenal number input serves as a marker to distinguish between stimuli to ACTH secretion inhibited by B at sites proximal and those inhibited by B at sites distal to this input.