Dafopoulos K, Mademtzis I, Vanakara P, Kallitsaris A, Stamatiou G, Kotsovassilis C, Messinis I E
Department of Obstetrics and Gynecology, University of Thessalia, 22 Papakiriazi Street, 41222 Larissa, Greece.
J Clin Endocrinol Metab. 2006 Feb;91(2):641-5. doi: 10.1210/jc.2005-1656. Epub 2005 Dec 6.
The endogenous LH surge is the result of the estrogen-positive feedback effect. However, the factors that are responsible for the termination of LH surge are not known.
The objective of the study was to investigate the mechanism that terminates the LH surge in women.
Eight normally cycling women (aged 42-48 yr) were investigated in two cycles, i.e. cycle 1 (control) and cycle 2. In cycle 2 total abdominal hysterectomy plus bilateral salpingooophorectomy was performed on d 3. In both cycles, estradiol was administered transdermally at the dose of 100 microg on d 3 and 150 microg on d 4 and 5. Blood samples were obtained every 12 h from d 3 to 5 and every 6 h thereafter until d 9.
In both cycles, after suppression of gonadotropins, the women displayed an endogenous LH surge. The time intervals between the commencement of estradiol treatment and the LH surge onset (73.5 +/- 1.5 vs. 76.5 +/- 2.5 h) and peak LH values (11.4 +/- 1.9 vs. 12.4 +/- 3.1 IU/liter) were comparable in the two cycles (mean +/- sem). After peaking, LH values decreased gradually in cycle 1, whereas in cycle 2 they remained stable and were higher than the corresponding values in cycle 1 (P < 0.05). Before the LH surge onset, estradiol values showed in both cycles a preovulatory pattern of changes, but starting 24 h after the onset of the LH surge, they were lower in cycle 2 (P < 0.05). Progesterone levels were similar in both cycles until the day of the LH surge onset, but in cycle 2 they declined thereafter and were lower than in cycle 1 (P < 0.05).
It is suggested that ovarian factors rather than exhaustion of pituitary reserves are important for termination of the endogenous LH surge during the normal menstrual cycle.
内源性促黄体生成素（LH）峰是雌激素正反馈作用的结果。然而，导致LH峰终止的因素尚不清楚。
本研究旨在探讨女性LH峰终止的机制。
对8名月经周期正常的女性（年龄42 - 48岁）进行两个周期的研究，即周期1（对照）和周期2。在周期2的第3天进行全腹子宫切除术加双侧输卵管卵巢切除术。在两个周期中，均于第3天经皮给予雌二醇100μg，第4天和第5天给予150μg。从第3天至第5天每12小时采集一次血样，此后每6小时采集一次，直至第9天。
在两个周期中，促性腺激素被抑制后，女性均出现内源性LH峰。两个周期中，雌二醇治疗开始至LH峰开始的时间间隔（73.5±1.5 vs. 76.5±2.5小时）和LH峰值（11.4±1.9 vs. 12.4±3.1 IU/升）相当（均值±标准误）。达到峰值后，周期1中LH值逐渐下降，而周期2中LH值保持稳定且高于周期1中的相应值（P < 0.05）。在LH峰开始前，两个周期中雌二醇值均呈现排卵前的变化模式，但在LH峰开始后24小时起，周期2中的雌二醇值较低（P < 0.05）。在LH峰开始之日前，两个周期中的孕酮水平相似，但在周期2中此后下降且低于周期1（P < 0.05）。
提示在正常月经周期中，卵巢因素而非垂体储备耗竭对于内源性LH峰的终止起重要作用。
