ANDROGEN REGULATION OF ADRENOCORTICOTROPIN AND CORTICOSTERONE SECRETION IN THE MALE-RAT FOLLOWING NOVELTY AND FOOT SHOCK STRESSORS

To examine mechanisms responsible for sex differences in hypothalamo-p ituitary-adrenal (HPA) axis responsiveness to stress, we studied the r ole of androgens in the regulation of the adrenocorticotropin (ACTH) a nd corticosterone (CORT) responses to foot shock and novelty stressors in gonadectomized (GDX) or intact male F344 rats. Foot shock or expos ure to a novel open field increased plasma ACTH and CORT, which was si gnificantly greater in GDX vs. intacts. Testosterone (T) or dihydrotes tosterone propionate (DHT) treatment of GDX animals returned poststres s levels of ACTH and CORT to intact levels. Estrogen treatment of GDX males further increased poststress CORT secretion above GDX levels. Th ere was no difference in the ACTH response of anterior pituitaries fro m intact, GDX, and GDX+DHT animals to CRF using an in vitro perifusion system. There were no differences in betamax or binding affinity of t ype I or 11 CORT receptors in the hypothalamus or hippocampus of intac t, GDX, or GDX+DHT groups. These data demonstrate an effect of GDX on hormonal indices of stress. The increased response in GDX rats appears to be due to the release from androgen receptor mediated inhibition o f the HPA axis. This inhibition by androgen is not due to changes in a nterior pituitary sensitivity to CRH, nor to changes in type I or type II corticosteroid receptor concentrations.