左旋18-甲基炔诺酮对大鼠雌激素水平及下丘脑雌激素受体阳性细胞的影响

Changes of estrogen level and estrogen receptor-positive neurons in levonorgestrel-treated rats

目的:观察左旋18-甲基炔诺酮(LNG)对大鼠雌激素(E)水平及下丘脑内雌激素受体(ER)阳性细胞的影响。方法:正常雌性SD大鼠分为给药对照组、给药组、停药对照组、停药组,应用免疫组织化学方法显示下丘脑ER阳性细胞并检测血清E浓度。结果:给药组较给药对照组E浓度下降,弓状核(Arc)、下丘脑腹内侧核(VMH)内ER阳性细胞的数量减少、光密度下降。停药后基本恢复正常。结论:长期LNG作用导致给药大鼠血清E水平下降;长期LNG作用引起大鼠下丘脑ER数量减少、活性减低,推测ER可能参与影响促性腺激素释放激素的分泌;停药后ER的形态学变化恢复正常,所以LNG的作用基本上是可逆的。

Objective： To explore the effect of LNG on estrogen level and estrogen receptor （ER） positive neurons in rats. Methods： Sprague Dawlay female rats were divided into the control group, long-term treated group, withdrawal group and control group for withdrawal.The forebrain sections for immunocytochemistry were fixed and embedded. The changes of serum estrogen level and estrogen receptor-containing neurons were observed. Results： Compared with the control group, the serum estrogen level as well as the density and the number of ER-positive cells in arcuate nucleus （Arc） and ventromedial hypothalamic nucleus （VMH） showed an obvious decline in the long-term treated group. These changes recovered to the normal level progressively in the withdrawal group. Conclusion： These results demonstrate that long-term treatment of oral contraceptive could induce serum estrogen level and decline ER positive cells in rat hypothalamus. ER in Arc and VMH may be associated with gonadotropin-releasing hormone secretion. After withdrawal with LNG, estrogen level and ER positive nucleus can be recovered.