FXR、IBABP在ICP孕鼠胆汁酸肠肝循环中作用机制的探讨

The Mechanism of Farnesoid X Receptor and IBABP in Enterohepatic Circulation of Bile Acids of Pregnant Rats with Intrahepatic Cholestasis

目的:通过苯甲酸雌二醇诱导建立孕鼠妊娠期肝内胆汁淤积症(intrahepatic cholestasis ofpregnancy,ICP)模型,检测法尼醇受体(farnesoid X receptor,FXR)、回肠胆汁酸结合蛋白(IBABP)在回肠上的表达,从胆汁酸肠肝循环角度探讨FXR通过IBABP在ICP中的作用机制。方法:孕15天SD大鼠30只随机分成两组:0.9%氯化钠(NS)组;苯甲酸雌二醇(estradiol benzoate,EB)处理组。用药前,用药后5天测血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、碱性磷酸酶(ALP)、总胆酸(TBA)、总胆红素(TBIL)、直接胆红素(DBIL)水平,测量胎鼠生理指标,观察肝脏形态学变化。分别应用逆转录多聚酶链式反应法(RT-PCR)及免疫组化法对回肠FXR及IBABP表达进行分析。结果:用药后EB组出现以下变化:孕鼠血清生化指标比用药前显著升高(P<0.05);孕鼠肝脏出现肝内胆汁淤积表现;胎鼠体重、胎盘重量减轻,胎死率增加,孕天数缩短(P<0.05);FXRmRNA、蛋白及IBABP mRNA、蛋白的表达高于NS组(P<0.05)。结论:雌激素具有明确的诱发孕鼠肝内胆汁淤积症的作用。雌激素诱导的胆汁淤积促进回肠FXR和IBABP(蛋白及mRNA)的增加表达,导致胆汁酸肠肝循环转运增加,进一步加重胆汁淤积,这可能是ICP发病机制之一。

Objective： To explore the mechanism of Famesoid X receptor （FXR） in ICP enterohepatic circulation by detecting the expression of famesoid X receptor（FXR） and IBABP in ileum from SD rat model of ICP induced by estradiol benzoate（EB）. Methods： 30 pregnant.SD rats at 15 days were randomly divided into experiment group and control group; subcutaneous injection of EB or isotonic Na chloride （NS） was given respectively for .5 days. Serum liver function indexes were measured 5 days before and after subcutaneous injection. Liver and ileum tissue was taken for histological analysis with light microscope by HE staining after delivery. The expression of FXR/IBABP protein in ileum was analyzed by immunohistochemical method and the expression of FXR/IBABP mRNA was analyzed by RTPCR. Results： The serous liver function index level in the experiment group increased significantly （ P 〈0.05）. Rats in experiment group showed intrahepatic cholestasis,with less fetal and placental weight, higher fetal death rate and shorter pregnancy period than those in control group （ P〈 0.05）. Protein and mRNA expression of FXR and IBABP were significantly higher in experiment group than in control group （ P 〈 0.05）.Conclusions： EB is the best candidate for inducing rat model of ICP. Cholestasis induced by estradiol benzoate increase FXR and IBABP expression in ileum,which transport more bile acids into pedal vein.This may be one of the mechanisms of ICP.