孕鼠暴露双酚A对仔鼠存活率、生殖激素及相关基因的影响

为了研究孕鼠在孕期暴露双酚A（bisphenol A，BPA）对仔鼠生殖激素及相关基因的影响，试验将40只昆明孕鼠随机分为A、B、C、D共4组，每组10只。其中A组为对照组，饲喂普通鼠粮；B、C、D组孕鼠整个妊娠期（妊娠1 d至分娩）分别按每只鼠每天50、500、2 500 mg/kg体重给予BPA，待孕鼠自然分娩，观察记录仔鼠死亡情况。至仔鼠性成熟（56日龄）剖杀仔鼠，摘取睾丸或卵巢称重并计算脏器指数，HE染色观察卵巢或睾丸组织结构的变化，ELISA试剂盒分析仔鼠血清睾酮（T）、促卵泡素（FSH）及雌二醇（E₂）水平，免疫组织化学方法检测仔鼠睾丸或卵巢Bax、Bcl-2蛋白的表达，实时荧光定量PCR检测仔鼠睾丸StAR、CYP11a或卵巢AMH、Kitlg mRNA表达。结果显示，孕鼠暴露BPA极显著增加了仔鼠死亡率（P<0.01），显著降低了仔鼠睾丸重（P<0.05）。ELISA检测结果表明，孕鼠暴露BPA极显著降低了仔鼠T（♂）及FSH（♀）含量（P<0.01），极显著升高了仔鼠（♀） E₂水平（P<0.01）。HE染色结果显示，随BPA剂量增加，仔鼠睾丸组织损伤严重，间质细胞减少；卵巢组织结构随BPA剂量增大，空泡逐渐增多，黄体颗粒数量逐渐减少。免疫组化结果显示，孕鼠暴露BPA增加了仔鼠睾丸或卵巢组织中Bax阳性蛋白表达，减少了Bcl-2阳性蛋白表达，显著降低了雄性仔鼠StAR mRNA表达量（P<0.05）；B、D组雄性仔鼠CYP11a mRNA表达量极显著降低（P<0.01），而C组CYP11a mRNA表达量极显著升高（P<0.01）；C、D组雌鼠Kitlg mRNA表达极显著降低（P<0.01），AMH mRNA表达量显著升高（P<0.05）。本试验结果表明，孕鼠妊娠期暴露不同剂量BPA增加了仔鼠死亡率，扰乱了生殖激素平衡和睾丸/卵巢中相关凋亡蛋白及生殖基因表达。

Effects of Maternal Exposure to Bisphenol A on Survival Rate,Reproductive Hormones and Relative Genes of Offspring Mice

This study was aimed to investigate the reproductive toxicity of bisphenol A (BPA) exposed to the mother on the offsprings mice. Forty pregnant Kunming mice were randomly divided into 4 groups, i.e. groups A, B, C and D with 10 mice in each group. Group A was the control group and the mice received conventional feeds, mice in groups B, C and D were given 50,500 and 2 500 mg/kg BW BPA in feedstuffs during the whole gestation period (from 1 d to parturition), respectively. The death rates of the offsprings were calculated every week. The offspring mice were sacrificed at 56 days of age (at puberty). The morphology of ovary and testicular tissues were observed with hematoxylin-eosin (HE) staining. The levels of estradiol (E₂), follicle stimulating hormone (FSH), testosterone (T) in mice serum were detected with ELISA Kit. The protein levels of Bax and Bcl-2 in ovary or testicular tissues were detected with immunohistochemistry, and the StAR,CYP11a mRNA levels in testicular tissues, the AMH, Kitlg mRNA levels in ovary were measured using Real-time PCR. The results showed that exposure of BPA to the mother extremely significantly increased the mortality (P<0.01),and significantly reduced the testicular weight of offspring mice (P<0.05). Maternal exposure to BPA extremely significantly reduced the levels of T (♂) and FSH(♀) (P<0.01),and extremely significantly elevated E₂ (♀) level in offspring mice (P<0.01). BPA exposure damaged the testicular with less leydig cells and ovarian tissues with more vacuoles and less corpus granules in offspring mice. Immunohistochemistry results revealed that maternal exposure to BPA increased the Bax protein level and decreased the Bcl-2 protein level of testicular and ovary tissues in offspring mice. BPA significantly reduced the StAR mRNA expression in male offsprings (P<0.05). However, the mRNA level of CYP11a in groups B and D extremely significantly decreased while group C showed an significant elevation in male offsprings (P<0.01). The expression levels of Kitlg mRNA in groups C and D were decreased extremely significantly in female offsprings (P<0.01), the AMH mRNA expression in groups C and D increased significantly (P<0.05). The conclusion indicated that pregnant mice exposed to different doses of BPA had harmful effects on survival rate in offspring mice, and impact the reproductive hormones, proteins and genes expression.