Effects of long-term steroid suppression on rat adrenal 5 alpha-reductase and 11 beta-hydroxylase activities and corticosterone production in vitro.

The effects of prolonged steroid suppression on adrenal 5 alpha-reductase and 11 beta-hydroxylase activities and corticosterone production in vitro was studied in adult male rats. Cortisone acetate was administered at a dose of 2.5 mg/rat daily for 30 days and after that time at a dose of 5 mg/rat every other day. Autopsies were performed on 3, 6, 9, 12, 15, 20, 30, 60 and 120 days of experiment. Cortisone treatment resulted in a decrease in corticosterone output by quartered adrenals and an earlier and more marked drop in corticosterone production by whole adrenal homogenates. Steroid suppression leads to a marked increase in adrenal 5 alpha-reductase activity assayed on 12,000 X g supernatant, however on 120 day of experiment activity of the enzyme was markedly lower if compared with the earlier time-interval studied. 11 beta-hydroxylase activity, as tested in mitochondrial fraction, on day 12 of experiment was even higher than in control rats and thereafter a marked decline occurred. The studies suggest that adrenal steroid 5 alpha-reductase activity may participate in adaptation of adrenals to a disturbed hormonal status of the organism induced by cortisone treatment.