Influence of Progestins on Ovarian Responses to Estrogen and Gonadotrophins in Immature Rats

Abstract

The influence of progesterone or certain synthetic progestins on ovarian response to estrogen and/or gonadotropin was studied in intact and hypophysectomized immature rats. No effect of progestins on ovarian follicular growth or luteinization was noted in hypophysectomized animals. In intact rats, ovarian luteinization was suppressed by progestins, and completely inhibited by progestin and estrogen in combination. It is concluded that progestins do not directly modify ovarian responses to estrogen or gonadotropin or the augmenting effect of both, but progestins do influence ovarian function by modifying the elaboration of endogenous pituitary gonadotropin.