微囊藻毒素-LR长时期低剂量暴露对雌性小鼠生殖功能的影响及其机制研究

Microcystin-LR (MC-LR) is one kind of monocylic heptapeptide toxin produced by cyanobacteria. Our recent study found that MC-LR could reach mammalian ovarian tissue, cause ovarian tissue damage, reduce ovarian weight, induce apoptosis of ovarian granulosa cells, decline the serum estradiol (E2) and disturb the estrous cycle. The results suggested that ovarian granulosa cells are the important target of female reproductive toxicity induced by MC-LR. Based on the previous work, this project is planed to carry out the following research. Firstly, the reproductive toxicity of MC-LR on female mice will be evaluated after long-term intake through drinking water in accordance with the WHO drinking water safety standards. Secondly, the transport route of MC-LR across the ovarian granulosa cell membrane should be ascertained by means of screening the Oatps present on cell membrane and investigating the correlation between Oatps and the transportation of MC-LR. Finally, we will establish the ovarian granulosa cell model of decreased E2 synthesis induced by MC-LR with the administration of FSH, determine the molecular mechanisms of decreased E2 synthesis, and discover the molecular targets of reproductive toxicity induced by MC-LR and available sensitive biomarkers. This study has great significance for raising public awareness on female reproductive toxicity of MC-LR and ensuring female reproductive health.

微囊藻毒素-LR（MC-LR）是由蓝藻产生的单环七肽毒素。申请人在近期研究中率先发现MC-LR能够进入哺乳动物卵巢组织，引起卵巢组织结构受损、重量减轻，卵巢颗粒细胞凋亡，血清雌二醇（E2）水平下降，动情周期紊乱，提示卵巢颗粒细胞是MC-LR雌性生殖毒性作用的重要靶细胞。本项目拟在前期基础上，开展以下研究：①参照WHO饮用水MC-LR安全标准，经饮水长时期染毒雌性小鼠，确认MC-LR长时期低剂量暴露对其雌性生殖功能的影响。②筛选卵巢颗粒细胞膜上表达的转运蛋白Oatps，验证其与MC-LR转运的相关性，明确MC-LR进入卵巢颗粒细胞的途径。③建立FSH刺激下MC-LR导致卵巢颗粒细胞合成E2下降的细胞模型，探明MC-LR干扰E2合成的分子机制，发现MC-LR生殖毒性作用的分子靶点及可利用的敏感的生物标志物。该研究对于提高人们对MC-LR雌性生殖毒性的认识，保障女性生殖健康具有重要意义。

环境污染对人类生殖健康的影响是当今全球关注的重要问题。近年来，随着水体富营养化进程加快、程度加剧，蓝藻水华频频发生，MC-LR源源不断释放入水，河流、湖泊、水库等许多饮用水源都面临MC-LR污染问题。本课题构建长期低剂量MC-LR染毒小鼠模型，首次发现通过饮用水长期摄入环境剂量MC-LR，卵泡闭锁增加，雌二醇和孕激素水平异常，动情周期紊乱，生殖能力下降，明确MC-LR具有生殖毒性。通过体外实验发现MC-LR能够进入卵巢颗粒细胞，卵巢颗粒细胞表达的Oatp5a1很可能与MC-LR的转运相关。MC-LR进入卵巢颗粒细胞后，激活MAPK通路，引起erk1/2磷酸化，抑制17β-HSD和CYP19a1基因和蛋白表达下降，从而抑制E2的合成引起生殖毒性损伤。研究获得了原创性结果，阐明了新机制，对于提高人们对MC-LR雌性生殖毒性的认识，保障女性生殖健康。