Endocrine activity of the postmenopausal ovary: the effects of pituitary down-regulation and oophorectomy.

The endocrine activity of the postmenopausal ovary and the effect of pituitary down-regulation were studied in a group of 35 postmenopausal women. All women underwent oophorectomy with or without hysterectomy. Fifteen women received a single dose of a depot GnRH agonist (GnRHa) 2 weeks before operation, whereas 20 women formed the control group. Peripheral venous levels of LH, FSH, estrone, 17 beta-estradiol, testosterone (T), androstenedione (A), sex hormone-binding globulin, and dehydroepiandrosterone sulfate were measured 2 weeks before, during, and 6 weeks after surgery. Ovarian venous blood was sampled during surgery. In the GnRHa and control groups, ovarian venous levels of A and T were significantly higher, and those of dehydroepiandrosterone sulfate and sex hormone-binding globulin significantly lower, compared to the peripheral levels. A significant decrease in T was found in the peripheral and ovarian vein samples during pituitary down-regulation with GnRHa. Six weeks after operation, peripheral T levels were significantly lower than those during surgery in the group that was down-regulated at the time of oophorectomy. We conclude that the postmenopausal ovary produces significant amounts of A and T, although only T contributes significantly to its peripheral serum levels. T production by the postmenopausal ovary is in part stimulated by the high levels of circulating gonadotropins, although pituitary down-regulation does not completely abolish androgenic activity.