Some aspects on pituitary function in human and rat anovulatory cycles.

To investigate the anterior pituitary function of human anovulatory cycles, hormonal environments were analyzed in an animal experimental model and women with anovulatory cycles. A specific antiserum to hypothalamic luteinizing hormone-releasing factor (LH-RF) was prepared in rabbits. Intravenous injection of 1.0 ml of this antiserum to 4-day cycling female rats on the proestrous day blocked ovulation in the following cycles without changing regular estrous cycles on vaginal smear. Thus experimental anovulatory cycles were induced in antiLH-RF serum-treated rats. In this experimental model, LH surge on the proestrous evening was blocked but LH and FSH were maintained at the basal levels. In human anovulatory cycles, serum LH and FSH levels were also not significantly reduced except during the period of LH surge, and blood estradiol-17beta levels were similar to the levels of women with normal ovulation. Serum progesterone levels were higher in the normal women after the expected day for ovulation. These data may indicate that the anterior pituitary is able to secrete its gonadotropins without stimulation by LH-RF and this tonic discharge of gonadotropins would maintain the basal levels of ovarian secretion of steroids.