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 p ituitary 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. Per ipheral venous levels of LH, FSH, estrone, 17 beta-estradiol, testoste rone (T), androstenedione (A), sex hormone-binding globulin, and dehyd roepiandrosterone 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 per ipheral levels. A significant decrease in T was found in the periphera l and ovarian Vein samples during pituitary downregulation with GnRHa. Six weeks after operation, peripheral T levels were significantly low er than those during surgery in the group that was down-regulated at t he time of oophorectomy. We conclude that the postmenopausal ovary pro duces significant amounts of A and T, although only T contributes sign ificantly to its peripheral serum levels. T production by the postmeno pausal ovary is in part stimulated by the high levels of circulating g onadotropins, although pituitary down-regulation does not completely a bolish androgenic activity.