降调节与卵泡发育同步化

Pituitary down-regulation and follicular synchronization

控制性卵巢刺激(COS)中垂体降调节的主要作用是预防早发内源性黄体生成素(LH)峰。降调节方案包括有促性腺激素释放激素激动剂(GnRH-a)长、短方案,以及GnRH拮抗剂(GnRH-ant)方案等。于前一周期黄体中期开始的GnRH-a长方案在获卵数和妊娠率等方面效果最好。GnRH-a长方案在体外受精-胚胎移植(IVF-ET)治疗中效果优于GnRH-a短方案和GnRH-ant方案,其原因之一据认为是后两方案中卵泡发育缺乏同步性,致可利用卵子和胚胎数减少。COS中同步化卵泡的关键在于外源性促性腺激素(Gn)启动前使窦卵泡处于卵泡刺激素(FSH)阈值下,其处理方案有GnRH长方案、类固醇预处理和GnRH-ant预处理等。本文就各种卵泡同步化方案及其优缺点进行简单回顾。

The key aim of pituitary down-regulation in controlled ovarian stimulation （COS） is to prevent premature endogenous luteinizing hormone （LH） surge. The down-regulation protocols include long and short GnRH agonist protocols, as well as GnRH antagonist protocol. The long GnRH agonist protocol starting in the midluteal phase of the preceding cycle give the best IVF results with regard to oocyte yield and pregnancy rates. This long protocol induces profound suppression of endogenous release of gonadotrophins during the early follicular phase, allowing the antral follicles to grow coordinately in response to exogenous gonadotrophins to accomplish simultaneous maturation. The short and GnRH antagonist protocols can abridge the duration and complexity of COS and improve patient compliance as compared with the reference long protocol for IVF. Nevertheless, the explanation for the poor IVF-ET outcome achieved with these two protocols compared with long protocol could be, at least in part, related to pre-existing asychronization of early antral follicles before the start of gonadotrophin administration. The steroid （oral contraceptive pill （OCP）, synthetic progestogen and natural estrogen） pre-treatment and GnRH-antagonist pre-treatment may be useful to suppress luteal FSH and reduce size differences among FSH-sensitive follicles during the early follicular phase. These approaches represent potential alternatives to synchronize multi-follicular development and improve ovarian stimulation results. However, larger studies are needed to confirm whether follicular growth coordination induced by steroids and premenstrual GnRH antagonist pre-treatment improve IVF-ET pregnancy rates with GnRH antagonist or short agonist protocols.