Influence of the pituitary-adrenal axis on the induced release of luteinizing hormone in rams.

Treatment of intact rams with ACTH increased plasma corticosteroids and significantly reduced the ability of LH releasing hormone (LHRH) to elicit the release of LH. Infusion of cortisol at a rate which increased plasma corticosteroid concentrations to above that observed after injection of ACTH did not affect the ability of LHRH to induce the release of LH. In adrenalectomized rams LH release in response to LHRH was inhibited during ACTH treatment but was not affected in the absence of ACTH. Therefore, ACTH reduced the responsiveness of the anterior pituitary gland to LHRH through a mechanism not involving the adrenal gland.