Influence of the ovary on parameters of LH secretion during the recovery from buserelin-induced desensitization

This study examined the effect of the ovary on LH pulsatility and on the secretory performance of gonadotrophs during the phase of recovery after treatment with buserelin, a GnRH analogue. We included 12 patients, who received buserelin (1.2 mg/day, intranasally for 3 months) as a reductive therapy for uterine leiomyomatosis prior to hysterectomy. Six patients were oophorectomized and the other 6 patients had their ovaries preserved. LH was measured in samples taken basally up to 36 days after suppression of buserelin. LH pulsatility was studied on day 9 along a 24-h cycle, and the response of the hormone to a double-stimulus GnRH test on days 0, 9, 20, and 34. The concentration of LH reached normal premenopausal levels after an average of 2 weeks in women with ovaries but increased until 4-5 weeks in oophorectomized patients. The pulsatility of LH on day 9 was similar for both groups, but parameters related to LH amplitude or to baseline secretory activity of gonadotrophs were higher in the oophorectomized women. The response of LH to the GnRH tests was also significantly higher in the oophorectomized group from day 9. The conclusions are as follows. (1) At the early stage of recovery from desensitization, as represented by day 9, LH pulsatility was not substantially influenced by the presence or absence of the ovary. (2) There was an increase in parameters related to the amplitude of the LH bursts in the oophorectomized women. Although a higher amplitude of the endogenous GnRH pulses cannot be discarded, most probably that difference is due to a higher sensitivity at a pituitary level, as reflected by the GnRH stimulation tests.