二甲双胍对PCOS大鼠子代生殖和代谢功能及基因表观遗传学修饰的影响

Polycystic ovary syndrome (PCOS) is the most common reproductive endocrine disease globally. Its pathogenesis and its possible influence on offspring are research hotspots in recent years. Firstly, the complicated and abnormal intrauterine environment of PCOS patients make it offspring at an increased risk of a variety of chronic diseases (such as diabetes, coronary heart disease and high blood pressure) and malignant diseases (such as endometrial cancer, ovarian cancer and breast cancer); Secondly, recent studies have demonstrated that abnormal genetic modifications may exist in oocytes of PCOS patients, and these abnormal genetic modifications may possibly continue to affect its offspring. Metformin can work on the AMPK pathway to reverse the above genetic modification changes, thus it may help to improve the prognosis of PCOS patients and their offspring. Recently, some scholars have queried the consensus about its underestimation of the metformin in treating PCOS, but currently we are still short of enough evidence to support it being used as a conventional first-line drug in PCOS patients. This project aimed to build four generation models of PCOS in rats. Then study the effects of PCOS on its offspring from reproductive and metabolic aspects, and detect the expression levels of PCOS related susceptible genes and the states of epigenetic modifications in PCOS offspring. In addition, by giving regular doses of metformin to parental rats, we wanted to explore whether metformin can reverse reproductive and metabolic abnormalities in offspring of PCOS rats, and to investigate its potential underlying mechanisms, so as to provide new ideas and evidences for the medical treatment of PCOS.

多囊卵巢综合征（PCOS）是最为常见的女性生殖内分泌疾病。其发病机制及其对子代可能存在的影响是近年来的研究热点。首先，PCOS患者妊娠时复杂的宫内异常环境可使其后代成年后多种慢性疾病（如糖尿病、冠心病及高血压）和肿瘤性疾病（如子宫内膜、卵巢癌及乳腺癌）的发病率显著增加；其次，已经证实PCOS患者卵母细胞存在异常的基因修饰改变，并可能以此对子代产生影响；而二甲双胍恰可作用于AMPK通路逆转上述改变，故可能有助于改善PCOS患者子代预后结局。近年来已有学者对PCOS共识中二甲双胍的定位提出质疑，但仍缺乏足够证据支持其作为PCOS患者的常规一线用药。本项目旨在通过构建PCOS大鼠四代传代模型，从生殖和代谢两方面研究PCOS对子代可能存在的影响，并检测子代PCOS相关易感基因表达水平及表观遗传学修饰状态；通过给予亲代大鼠常规剂量二甲双胍，探讨二甲双胍是否可逆转PCOS大鼠子代存在的生殖及代谢异常。

多囊卵巢综合征是以慢性或持续性无排卵、高雄激素血症、卵巢多囊改变为特征的生殖内分泌紊乱疾病，在无排卵性不孕女性中发病率高达90-95%，在青春期和育龄女性中发病率约为10%。二甲双胍是PCOS常用的临床治疗药物，其主要通过降低患者胰岛素抵抗水平，缓解胰岛素抵抗（insulin resistance, IR），进而改善患者排卵障碍及高雄激素血症。目前关于PCOS患者后代的研究甚少，尚无关于二甲双胍干预后对PCOS后代影响的研究。本研究通过来曲唑缓释剂成功诱导了PCOS-IR大鼠传代模型，研究提示二甲双胍应用于无糖耐量异常或二型糖尿病且有生育需求的PCOS患者是有益的；研究发现肥胖的PCOS-IR大鼠子一代雌鼠进入性发育期后肥胖发生率高，而经二甲双胍治疗后，能显著降低其子一代雌鼠进入性发育期后的肥胖发生几率，与PCOS发病密切相关的INSR基因、FSHR基因在PCOS-IR大鼠子一代雌鼠性成熟后表达异常，但在子二代雌鼠中表达无差异，子一代、子二代各期代谢水平及性成熟后性激素水平表达无明显异常，同时与PCOS发病相关基因（PPARG、HDAC3、NOCR1）在子一代雌鼠存在异常甲基化水平，但在子二代无明显异常，故提示PCOS发病与基因及非遗传因素等均存在密切关系。通过对PCOS-IR大鼠子一代进行高脂饮食研究发现，高脂饮食能增加子一代雌鼠多囊卵巢综合征发病风险。研究尝试将与噻唑烷二酮分子结构类似的植物性激素——脱落酸用于PCOS-IR大鼠的治疗，研究结果发现，其具有与二甲双胍同样的调节代谢异常的作用，但其降低PCOS-IR大鼠高雄激素血症的作用优于二甲双胍，因此，脱落酸对PCOS的药物治疗提供了新思路，希望通过更深入的研究探讨其广阔的临床应用前景。