摘要:
非洲爪蟾卵母细胞生发泡破裂(GVBD)是生物学上研究卵细胞成熟过程及其机制的良好模型。由于GVBD受激素的调控,曾有研究将孕酮诱导的非洲爪蟾GVBD试验用于内分泌干扰物的筛查。通过预注射人体绒毛膜促性腺激素(HCG)提高非洲爪蟾卵母细胞对孕酮的敏感性、缩小个体差异,缩短试验时间等优化GVBD试验方法;并选用甲氧氯作为阳性参照物对优化的方法进行验证,最后用此方法研究了米非司酮、来曲唑、咪鲜胺3种化学物质对孕酮诱导GVBD的影响。结果发现,甲氧氯对GVBD的发生具有明显抑制作用,随着剂量的增加抑制作用增强,显示优化方法的可靠性。米非司酮作为孕酮受体拮抗剂,没有表现出抑制GVBD的效应,证明孕酮诱导爪蟾GVBD并非完全由孕酮受体(PR)介导。同时,来曲唑和咪鲜胺对孕酮诱导爪蟾GVBD没有影响,显示此两种物质在孕酮诱导GVBD过程中不具有内分泌干扰作用。
Abstract:
Germinal vesicle breakdown (GVBD) of Xenopus laevis oocytes is a good model for studying the process and mechanism of oocyte maturation. Because the occurrence of GVBD is regulated by hormones, progesterone-induced Xenopus GVBD assay has been used for screening endocrine disruptors. In the present study, the GVBD assay was optimized by pre-injecting human chorionic gonadotrophin (HCG) to improve the sensitivity of Xenopus oocytes to progesterone and reduce the difference in the sensitivity among individuals, and by shortening the experiment time. Methoxychlor, as a positive reference, inhibited progesterone-induced GVBD in a concentration-dependent manner, demonstrating that the optimized assay was reliable. Mifepristone, as a progesterone receptor antagonist, had no inhibitory effect on progesterone-induced GVBD, suggesting that progesterone-induced GVBD could not be mediated completely by progesterone receptor. In addition, prochloraz and letrozole had no influence on Xenopus GVBD, showing no endocrine-disrupting activity in the process of Xenopus GVBD.
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