Schubert C, Nishino Y, Michna H
Forschungslaboratorien der Schering AG Berlin, Germany.
Ann Anat. 1995 Mar;177(2):139-46. doi: 10.1016/S0940-9602(11)80061-0.
The present study was undertaken to investigate whether inhibition of ovulation, which is known to occur after treatment with progesterone antagonists, is due to the effect of high levels of prolactin. Therefore, rats with 4-day cycles were treated with the antiprogestin, Onapristone (ON), once daily starting on the evening of estrus. It was detected that the profile of peripheral prolactin levels during the treatment with ON was not remarkably different from that found in the controls. Furthermore, bromocriptine, a prolactin antagonist, was not able to reverse the antiovulatory potency of ON. It is concluded that the antiovulatory effect of ON might not be related to changes in the level of prolactin. Nevertheless, prolactin levels remained high after the preovulatory surge. Thus, we cannot exclude the possibility that PRL plays a role in the induction of anovulatory cycles observed during long term treatment. In animals treated for the length of one cycle we found that the preovulatory LH surge decreased but it remains questionable whether this contributes to the inhibition of ovulation by ON. Interestingly, basal LH, androgen and estrogen levels were elevated. Accordingly, we favour the idea that LH stimulates the theca interstitial cells to produce excessive amounts of androgens which may be aromatized into estrogens. These high levels of androgens and estrogens may contribute to the antiovulatory mechanism of ON by disturbing physiological follicular development. In fact, a morphometrical analysis revealed an increase in the volume density of late tertiary follicles. The increased progesterone levels may also be related to high basal LH levels.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究旨在探讨已知在用孕酮拮抗剂治疗后发生的排卵抑制是否归因于高水平催乳素的作用。因此，对周期为4天的大鼠从发情期晚上开始每天用抗孕激素奥那司酮（ON）治疗一次。检测发现，在用ON治疗期间外周催乳素水平的变化情况与对照组并无显著差异。此外，催乳素拮抗剂溴隐亭无法逆转ON的抗排卵效力。得出的结论是，ON的抗排卵作用可能与催乳素水平的变化无关。然而，排卵前激增后催乳素水平仍保持较高。因此，我们不能排除催乳素在长期治疗期间观察到的无排卵周期诱导中起作用的可能性。在接受一个周期长度治疗的动物中，我们发现排卵前促黄体生成素（LH）激增有所下降，但这是否导致ON抑制排卵仍存疑问。有趣的是，基础LH、雄激素和雌激素水平升高。因此，我们支持这样的观点，即LH刺激卵泡膜间质细胞产生过量雄激素，这些雄激素可能会 aromatized 为雌激素。这些高水平的雄激素和雌激素可能通过干扰生理性卵泡发育而促成ON的抗排卵机制。事实上，形态计量学分析显示晚期三级卵泡的体积密度增加。孕酮水平升高也可能与基础LH水平高有关。（摘要截选至250字） 注：“aromatized”此处可能有误，未查到准确释义，可能是“芳香化”之类的意思。
