Estrogen feedback in normal and sulpiride-induced hyperprolactinemic postmenopausal women

Feedback effect of estrogen on gonadotropin secretion was studied in normal and sulpiride-induced hyperprolactinemic postmenopausal women. Twelve normoprolactinemic postmenopausal women were administered 40 micrograms/day of ethinyl estradiol (EE2) orally throughout the study. On the 4th week of the study, daily doses of 200 micrograms EE2 were also given to each subject for 4 days. Twelve postmenopausal women were given sulpiride orally in a daily dose of 150 mg throughout the study. Serum levels of prolactin were raised in all 12 subjects given sulpiride. In the 12 sulpiride-induced hyperprolactinemic postmenopausal women, EE2 was given in the same manner as in normal postmenopausal women. The negative feedback effect of estrogen with low doses of EE2 (40 micrograms/day for 4 weeks) and the positive feedback effect of estrogen after the subsequent administration of EE2 (200 micrograms/day for 4 days) were demonstrated in both normoprolactinemic and hyperprolactinemic groups. The result of the present study suggests that sulpiride-induced hyperprolactinemia does not affect the negative and positive feedback effect of estrogen in postmenopausal women.