Induction of follicle-stimulating hormone (FSH) receptors in rat ovaries by estrogen priming.

Estrogen pretreatment of hypophysectomized immature rats stimulated granulosa cell proliferation and enhanced FSH binding to the ovary in vivo. The present studies were undertaken to ascertain whether estrogen pretreatment altered the number of specific FSH receptor sites per ovarian cell, resulting in increased FSH binding. Cell suspensions were prepared from the ovaries of groups of rats pretreated with graded doses of 17beta-estradiol. The isolated cells contained specific FSH receptors with high affinity for FSH. The results of these studies clearly showed that the number of specific FSH receptors per ovarian cell was unaffected by pretreatment with graded doses of 17beta-estradiol or with diethylstilbestrol. The enhanced in vivo FSH binding was solely the result of estrogen-induced proliferation of granulosa cells with a fixed number of specific FSH receptors per cell.