Receptors for sex steroids in the primate corpus luteum. New insight into gonadotropin and steroid action

The evidence is compelling for progesterone receptor (PR) expression in the primate corpus luteum during the menstrual cycle, based on three experimental approaches: (a) immunocytochemistry, (b) radioligand binding to steroid-depleted tissue, and (c) reverse transcription-polymerase chain reaction or ribonuclease protection assay. This information is providing the impetus for studies on possible receptormediated roles for progesterone to control periovulatory events (including follicle rupture and luteal development) and the functional lifespan of the corpus luteum. Similar experiments suggest that estrogen receptors are nondetectable in the corpus luteum. Thus, "classic" receptor-mediated actions of estrogen, such as promoting PR expression, are not apparent; rather, the midcycle surge of LH assumes the role of stimulating PR expression in luteinizing granulosa cells. The recent discovery of androgen receptor expression in primate luteal tissue should lead to studies on the heretofore unsuspected actions of androgens in the corpus luteum.