Karsch F J, Battaglia D F
Reproductive Sciences Program and Department of Physiology, University of Michigan, Ann Arbor, MI 48109-0404, USA.
Reprod Suppl. 2002;59:101-13.
This review summarizes a series of experiments that address mechanisms by which endotoxin, a commonly used model of immune/inflammatory challenge, disrupts the oestrous cycle of the ewe. Initial studies in ovariectomized ewes demonstrated that endotoxin inhibits pulsatile LH secretion and that this suppression is achieved in two ways: (i) decreased episodic secretion of GnRH and (ii) reduced pituitary responsiveness to GnRH. These findings led to the hypothesis that the inhibition of pulsatile LH secretion can account for the disruptive effects of endotoxin on the oestrous cycle. Follow-up studies to test this hypothesis revealed that suppression of LH pulsatility during the follicular phase is clearly one means by which endotoxin disrupts the oestrous cycle. However, these studies also provided evidence that endotoxin can impair ovarian follicular responsiveness to gonadotrophin stimulation and inhibit the oestradiol-induced preovulatory LH surge. Collectively, these disturbances in hypothalamo-hypophyseal-ovarian function interrupt the preovulatory chain of events and thereby contribute to disruption of the ovarian cycle in response to this immune/inflammatory challenge.
本综述总结了一系列实验，这些实验探讨了内毒素（一种常用的免疫/炎症刺激模型）扰乱母羊发情周期的机制。对去卵巢母羊的初步研究表明，内毒素会抑制促黄体生成素（LH）的脉冲式分泌，且这种抑制通过两种方式实现：（i）促性腺激素释放激素（GnRH）的阵发性分泌减少；（ii）垂体对GnRH的反应性降低。这些发现引出了一个假说，即LH脉冲式分泌的抑制可解释内毒素对发情周期的破坏作用。为验证这一假说而进行的后续研究表明，卵泡期LH脉冲性的抑制显然是内毒素扰乱发情周期的一种方式。然而，这些研究也提供了证据，表明内毒素会损害卵巢卵泡对促性腺激素刺激的反应性，并抑制雌二醇诱导的排卵前LH峰。总的来说，下丘脑 - 垂体 - 卵巢功能的这些紊乱中断了排卵前的一系列事件，从而导致在这种免疫/炎症刺激下卵巢周期的破坏。
