Feedback of estrogen in postmenopausal women

The effect of exogenous estrogen on gonadotropin secretion was studied in postmenopausal women. Twelve postmenopausal Japanese women were administered 40 micrograms/day of ethinyl estradiol (EE) orally throughout the study. The ages of the volunteers ranged between 51 and 86 years. In the fourth week of the study, a daily dose of 200 micrograms of EE was also given orally to each subject for 4 days. The original administration of 40 micrograms/day of EE resulted in a gradual decline in both FSH and LH during the treatment. The degree of change in percent in decrease of FSH release was greater than that of LH release. When EE 200 micrograms/day was also given for 4 consecutive days a positive feedback action in both the FSH and LH levels was evident. The duration to the peak of the positive feedback action in LH and FSH was 5.3 and 4.4 days, respectively. These results suggest that the negative and positive feedback actions of estrogen on FSH and LH release are preserved in postmenopausal women.