Progesterone feedback in normal and sulpiride-induced hyperprolactinemic postmenopausal women

The feedback effect of progesterone on pituitary gonadotropin release was investigated in ten normal and ten sulpiride-induced hyperprolactinemic postmenopausal women. Forty micrograms of ethinyl estradiol (E2) was administered orally throughout the study. After E2 pre-treatment, 25 mg of progesterone was administered intramuscularly and serum concentrations of LH and FSH were assayed at 4, 8, 12, 24, and 48 hours after injection. A positive feedback effect of progesterone on gonadotropin release was demonstrated in five normoprolactinemic postmenopausal women and in six sulpiride-induced hyperprolactinemic women. These results suggest that the positive feedback effect of progesterone is maintained in sulpiride-induced hyperprolactinemic postmenopausal women as well as in normoprolactinemic postmenopausal women.