Effects of Gonadal Hormones on Adrenocortical Secretion of 5α-Reduced Metabolites of Corticosterone in the Rat

Studies were conducted to evaluate the effects of gonadal hormones on adrenal steroid secretion in vivo in both male and female rats. Following orchiectomy, corticosterone secretion declined despite an increase in adrenal wt. Secretion of 5α—dihydrocorticosterone (DHB) and 3β— 5α—tetrahydrocorticosterone (Compound R) increased significantly. Each of these effects of orchiectomy was reversed by replacement with testosterone. Ovariectomy also produced a fall in corticosterone output concomitant with increases in DHB and Compound R secretion. Secretion of DHB exceeded that of Compound R in castrates of both sexes. Estradiol administration reversed the effects of ovariectomy. The effects of gonadal hormones on steroid secretion paralleled in vitro changes in adrenal 5α—reductase activity. These observations establish the functional importance of 5α—reductase activity as a site at which the gonadal hormones influence the composition of adrenocortical secretory products in vivo. (Endocrinology91: 1523, 1972)