Short-term effects of ovariectomy: the opioid control of LH secretion in fertile climateric and postmenopausal women

The aim of this study was to evaluate the activity of opiate receptors involved in the regulation of LH secretion in relationship to ovariectomy. Menstruating fertile (n = 5) and climacteric (n = 7) patients and postmenopausal (n = 5) women who underwent therapeutical bilateral ovariectomy were studied in the first week postsurgery and LH plasma levels were evaluated after naloxone (4 mg in bolus plus 4 mg infusion/90 min), LHRH (10 micrograms + 10 micrograms iv) and saline administration. Two groups of fertile (n = 6) and postmenopausal (n = 6) subjects were studied as controls. Since the LH responsiveness to naloxone was impaired in climacteric patients after ovariectomy, the test was repeated in 5 of them after 1 and 6 months of estrogen-gestagen treatment (conjugated estradiol + noretisterone acetate), showing a significant increase in all patients in both cases. In four subjects treated with only gestagen, naloxone was still unable to significantly modify LH plasma levels. These results indicate that ovariectomy affects the activity of opiate receptors, resulting in the first week postsurgery LH rise inversely related to basal LH levels. Furthermore, these results indicate that one or six cycles of estrogen-gestagen treatment in ovariectomized patients similarly induces a restoration of the opiate receptors neuroendocrine activity.