阴离子通道CFTR在双酚A致精子损伤中的作用及机制研究

Human semen quality has been reported to decrease during the recent half century, partly contributed by environmental pollutants. Our previous epidemiologic studies indicated that people were ubiquitously exposed to Bisphenol A (BPA) and consequently human sperm quality was imparied. Our studies in vitro also showed that BPA inhibited spermatozoa capacitation and acrosome reaction in mice, decreased the expression levels of cAMP and CFTR (transmembrane conductance regulator, a cAMP-dependent ion channel expressed in epithelial cell membranes), all in dose-response relationships. Sertoli cells were also indicated to be decreased on their expression rates of CFTR in vitro, and apoptosis rate rose in our pilot study..Though the exact mechanisms remain unknown, we hypothesize on the evidences mentioned above that BPA might disrupt cAMP/CREB signaling pathway, decrease CFTR expression level, block the passageway of Cl- and HCO3-, impair Sertoli cells and spermatid, leading to the adverse effect of BPA on spermatogenesis, spermioteleosis and capacitation..In this proposal, a case-control study on fertility/infertility men and integral experiment on CFTR knockout mice are adopted for analysis on their sperm quality and levels of BPA exposure, cAMP/CREB pathway, membrane potential, spermatid-related and Sertoli cell-related cytokines..This study will elucidate the role and mechanism of CFTR in the adverse process of BPA on sperm quality. The present study will exploit novel research field of exocrinology for reproductive medicine. The development of new technology of fertility and contraception can also benefit from the study.

人类精子质量在近半个世纪的持续下降部分地与环境因素有关。我们已发现人们普遍接触环境污染物双酚A(BPA)，导致精子质量下降；BPA抑制动物精子细胞获能和顶体反应，下调cAMP和cAMP依赖的阴离子通道囊性纤维化跨膜转导调节因子(CFTR)表达；降低Sertoli细胞的CFTR表达率，促进凋亡。其具体机制未明。基于上述结果，我们推测BPA通过cAMP/CREB通路降低CFTR水平，阻碍Cl-及HCO3-离子通道，损伤Sertoli细胞和精子细胞，影响精子发生、成熟。本项目通过不育男性的病例-对照研究和CFTR基因敲除小鼠的整体实验，检测精子质量及其CFTR表达水平、信号通路、细胞膜电位、精子细胞及Sertoli细胞的相关神经因子、生长因子，以明确CFTR在BPA损伤精子质量中的作用，为生殖医学拓展外分泌学领域，有助于开发新的生育和节育技术。

全球男性精子质量呈持续下降趋势，其原因和机制复杂多样，接触双酚A（BPA）即是此类重要的环境因素。我们前期实验研究发现，BPA抑制动物精子细胞获能和顶体反应可能与阴离子通道囊性纤维化跨膜转导调节因子(CFTR)有关。.本项目通过细胞染毒实验及人群研究，检测精子质量、CFTR表达水平及相关信号通路、Sertoli细胞的相关神经因子、生长因子，以阐明其机制并对相关领域进行了探索，为防治男性不育提供理论基础。.结果显示：1、各BPA染毒组的小鼠精子细胞存活率、获能率、顶体反应率均显著下降，且与cAMP, p-CREB和CFTR的蛋白表达水平显著相关。染毒小鼠睾丸支持细胞存活率均显著降低；染毒时间为24h时，CFTR表达水平在100 ug/mL以上组均显著升高，但LDH、痛敏肽水平下降。2、在396人的横断面研究中，吸烟、运动、酒精摄入、使用塑料袋存放肉类制品以及食用蔬果均与精液参数显著相关，尤其是香菜类蔬菜可能对精子活力有保护和促进作用。3、对15例弱精症患者及15例对照的精液分析发现，CFTR水平升高，ATG-5、cAMP、LDHA、p-CREB降低。4、相关探索性研究发现，前列腺癌细胞系于双酚A中染毒24小时， cAMP浓度、CFTR表达水平、ATP浓度显著降低，凋亡相关基因表达水平改变，细胞凋亡水平上升。.本研究表明：1、CFTR可能与BPA所致精子活性下降有关；双酚A对睾丸支持细胞有毒性作用，影响支持细胞对精子细胞的能量供给与营养支持。2、精液质量可能与吸烟、饮酒、肉类制品存放方式和蔬菜水果食用频率相关。香菜类蔬菜可能对精子活力有保护和促进作用。3、弱精症患者的精液中CFTR水平升高，能量代谢及自噬水平下降。4、细胞第二信使cAMP及阴离子转运蛋白CFTR与BPA致前列腺癌有关。