Steroid control of gonadotropin secretion.

Current knowledge about the mechanism and site of action of estradiol (E2) and progesterone (P) during the menstrual cycle and the physiological role of androgens is reviewed. In normal women, the positive feedback effect of E2 at the pituitary level is the principal event of the follicular phase inducing the LH surge. P, by its negative feedback at the hypothalamic level and by its positive feedback at the pituitary level regulates GnRH and LH secretion during the luteal phase. Androgens do not directly play a role in gonadotropin regulation.