Neuroendocrine regulation of stimulated ACTH secretion

Two models of corticosteroid inhibition of stimulus-induced ACTH secretion are discussed. Modulation of ACTH secretion by a nonsteroidal factor related to adrenal mass is reviewed. Experiments are presented that compare feedback inhibition of ACTH affected by corticosterone and by adrenal mass. Use of two stimuli to ACTH secretion and manipulation of two feedback signals allow the conclusion that only one of the steroid feedback models will satisfy the data, and that corticosteroid feedback inhibition of stimulus-induced ACTH secretion must be exerted at at least two sites in the central nervous system.