Estrogen Treatment of Immature Rats Inhibits Ovarian Androgen Production in Vitro*

Publisher Website
Google Scholar
Abstract
The effects of estrogen treatment of intact vs. hypophysectomized immature female rats on the subsequent in vitro steroidogenic responses of the ovary to LH and dibutyryl cAMP were studied. Treatment of intact rats with 17β-estradiol (E2; 1 mg) for 3 days inhibited the ability of the ovaries to respond to LH with the production of testosterone but not progesterone, whereas both LH-induced testosterone and progesterone levels were attenuated by E2 in hypophysectomized animals. Addition of dibutyryl cAMP to the incubation media of ovaries from the E2-treated rats (both intact and hypophysectomized) markedly stimulated progesterone production but failed to elicit any significant production of testosterone. Ovaries from E2-treated hypophysectomized rats were deficient in converting exogenous progesterone to testosterone. In the E2- treated intact rats, the thecal cells of the largest follicles accumulated significantly greater quantities of progesterone in response to LH when compared to those from similarly sized follicles from control rats, suggesting that these cells were indeed viable and functional. These results strongly suggest that estrogen may inhibit ovarian androgen formation at an enzymatic step(s) in the biosynthetic pathway of androgens from their C21- precursors, and support the proposal that estrogen may act within the ovary to modulate its own production.