双酚A诱导雄性中国林蛙肝细胞雌激素受体表达和卵黄蛋白原合成

为探讨双酚A(bisphenol A,BPA)对雄性两栖动物肝细胞中雌激素受体(estrogenreceptor,ER)表达和卵黄蛋白原(vitellogenin,VTG)合成的影响,将中国林蛙(Ranachensinensis)雄性成体分别持续暴露于10-7、10-6、10-5mol/LBPA水体中10、20、30d,设10-9、10-8mol/L雌二醇(E2)为阳性对照。用原位杂交技术检测ERmRNA在肝细胞中的表达定位,用免疫组织化学技术检测肝细胞中ER和VTG蛋白的表达。结果显示,各BPA和E2处理组肝细胞中均有ERmRNA阳性反应,ER和VTG蛋白的表达相对值均显著高于空白对照组。在同一暴露时间,ER和VTG表达值是随着BPA浓度的增加呈增高趋势。在同一BPA浓度,VTG表达值是随暴露时间的延长呈增高趋势,而ER表达值则无显著性变化。这些表明BPA可以通过诱导雄性中国林蛙肝细胞的ER高调导致VTG合成,但其效应远低于E2。

Estrogen receptor expression and vitellogenin synthesis induced in hepatocytes of male frogs Rana chensinensis exposed to bisphenol A

The effects of bisphenol A (BPA) on estrogen receptor (ER) and vitellogenin (VTG) in hepatocytes of male amphibians have attracted significant attention in recent years. Adult male frogs Rana chensinensis were exposed to different concentrations of 10(-7), 10(-6) and 10(-5) mol/L BPA consecutively for 10, 20, and 30 d, respectively. We used 10(-9), 10(-8) mol/L 17β-esradiol (E(2)) as positive controls. The expressions of ER mRNA in the hepatocytes were detected by in situ hybridization, and ER and VTG protein were detected by immunohistochemistry. The results showed that positive effects of ER mRNA were detected in all BPA and E(2) treatment groups. Compared with the control group, the expression level of ER and VTG protein increased significantly in the hepatocytes of R. chensinensis. Both ER and VTG expression exhibited BPA dose-dependence for the same exposure time. For the same concentration of BPA treatment, VTG synthesis markedly increased with prolonged treatment, whereas the expression of ER did not significantly fluctuate. It is suggested that BPA caused the synthesis of VTG by inducing ER up-regulation in the hepatocytes of male R. chensinensis, but its estrogenic activity was much lower than E(2).