尼伯金酯诱发小鼠卵巢囊肿的毒理学研究

Parabens are a group of substances commonly employed as preservatives, which are ubiquitously detected in environments at high levels. Some studies shows that high concentrations of parabens were detected in urine, blood and tissues of common populations. Parabens are known as endocrine disrupting chemicals with binding activities on several nuclear receptors. Our recent study found that the commonly used parabens (including methyl-, ethyl-, propyl-, and butyl-paraben) significantly increased the incidence of ovarian cysts in mice at the real levels of human exposure, and transgenerational effects were observed in the paraben treated mice and their untreated offspring. Based on the previous discovery, as well as the fact that high incidence of ovarian cysts occurs in human populations but its pathological mechanisms are still unclear, this project is designed to determinate the relationships between paraben-exposures, ovarian cysts and fertility, and reveal the toxicological mechanism of ovarian cysts caused by parabens via multi - generation experiments using mice. We will study the mechanisms involved in endocrinology and transcriptomics of the ovarian cysts caused by parabens, and investigate the epigenetics of transgenerational effects caused by parabens, using the tools of endocrinology, transcriptomics and epigenetics, and methods of hormone analysis, pathological sections, chemical instrumental analysis and others. This project will provide valuable data and mechanisms for the management of parabens and the development of new reasonable standards for uses of parabens. The study of ovarian cysts in mice caused by parabens at real levels of human exposure will provide a typical case in the academic area of human health effects of endocrine disrupting chemicals. The obtained data and mechanisms will be helpful to better understand the high incidence of human ovarian cysts.

尼伯金酯是环境中普遍存在、人体暴露量大、内暴露浓度高的一类化学物质，也是具有多种受体结合活性的典型内分泌干扰物。本项目组前期工作发现，四种常用尼泊金酯（尼伯金甲、乙、丙、丁酯）在现实人体暴露剂量即可导致小鼠卵巢囊肿，并发现尼伯金酯致小鼠卵巢囊肿具有明显传代效应；然而，由尼泊金酯致小鼠卵巢囊肿造成的生殖危害尚缺乏细致研究，尼泊金酯诱发卵巢囊肿的毒理机制尚不清楚。为此，本项目拟通过低剂量尼泊金酯小鼠多代实验，深入解析尼伯金酯、卵巢囊肿、生殖力下降之间的关系，并结合内分泌学、转录组学和表观遗传学的研究手段，借助病理切片、免疫组化等常规方法，重点解析尼泊金酯诱发卵巢囊肿的内分泌学和分子毒理学机制，全面探索尼泊金酯致卵巢囊肿传代效应的表观遗传学原理；为该类物质的管理和标准制定提供数据支持，为内分泌干扰物健康效应研究提供现实人体暴露剂量下致病的动物实验案例，为探究人类卵巢囊肿高发的原因提供重要参考。

本项目圆满完成了项目的设计目标和内容，获得了预期结果。通过多代小鼠长期暴露实验，项目确定了4种常用尼泊金酯造成小鼠卵巢囊肿的主要类型及发病率情况，发现人体暴露水平及更低剂量的尼泊金酯即可引起卵巢囊肿，并且因此造成不孕症。项目量化了尼泊金酯致卵巢囊肿和不孕症的相关剂量效应关系。同时我们通过子代恢复实验发现尼泊金酯诱发卵巢囊肿存在传代效应。我们利用激素水平分析、组织病理分析、转录组测序、全基因组DNA甲基化测序和GTT、ITT实验等技术手段，发现了尼泊金酯诱发卵巢囊肿的原因与尼泊金酯引起胰岛素抵抗、高胰岛素血症、糖耐量损伤等相关，这与人群流行病学结果吻合。本项目系统揭示了尼泊金酯等物质通过结合ERRg受体，干扰胰岛素调控ERRg的蛋白质磷酸化和活性，进而造成空腹高胰岛素血症和胰岛素抵抗，造成胰脏组织和胰岛组织损伤，最终造成糖尿病症状和卵巢囊肿。对暴露尼泊金酯小鼠及其未暴露子代小鼠精子DNA甲基化分析发现，暴露尼泊金酯后，精子DNA甲基化改变基因显著富集于胰岛素抵抗、胰岛素信号通道、糖尿病通道和类固醇激素合成通道等，首次揭示了尼泊金酯的表观遗传效应；同时在亲代暴露但子代未暴露小鼠精子DNA甲基化分析中发现，尼泊金酯暴露可引起后代I型糖尿病相关基因的甲基化改变，这为I型糖尿病的发病机制演技提供了重要线索。我们的研究用大量数据表明尼泊金酯作为食品添加剂具有严重的健康风险，有必要加以禁止。