FXR和BSEP在阻塞性黄疸大鼠肝细胞中的表达及其意义

Expressions of FXR and BSEP in liver cells of rats with obstructive jaundice and their significances

目的:研究胆盐输出泵(BSEP)在阻塞性黄疸肝细胞表达过程中的变化及其与阻塞性黄疸高胆汁酸血症的关系,探讨法尼酯衍生物X受体(FXR)的活性及内毒素(ET)对BSEP表达的影响。方法:36只健康SD大鼠随机分为假手术组(Sham)、胆总管结扎组(CBDL)和胆总管结扎再通组(BR),建立大鼠阻塞性黄疸模型,检测各时相点血清总胆红素(TBIL)、总胆汁酸(TBA)和ET水平;用免疫组织化学法观察各组大鼠肝组织FXP和BSEP蛋白的表达,用平均积分光密度(IOD)法检测FXR和BSEP蛋白的表达水平;线性相关分析FXR、TBA、ET和BSEP之间的定量关系。结果:Sham组大鼠术后各时间点血清TBIL、TBA及ET水平无明显变化(P>0.05);CBDL组大鼠胆总管结扎术后,TBIL、TBA及ET水平显著增高(P<0.01);BR组大鼠胆道再通术后TBIL、TBA及ET水平逐步下降,术后7d组TBIL、TBA接近Sham组水平(P>0.05),ET仍高于Sham组水平(P<0.05)。肝组织中FXR蛋白表达水平在Sham、CBDL和BR组中呈逐渐缓慢增高趋势,但各组间比较差异无统计学意义(P>0.05)。肝组织中BSEP蛋白表达水平在Sham和CBDL组中呈下降趋势,BR组先下降后上升,但与Sham组比较差异无统计学意义(P>0.05)。FXR蛋白表达与血清TBA水平呈正相关关系(r=0.303,P<0.05),FXR与BSEP蛋白表达呈负相关关系(r=-0.359,P<0.05),BSEP蛋白表达与血清ET水平呈高度负相关关系(r=-0.412,P<0.01)。结论:阻塞性黄疸时FXR在BSEP表达调控中并非起主要作用,而是ET致炎症介质的释放下调了BSEP表达。

Objective To observe the changes of transport protein Farnesoid X receptor （FXR） and bile salt export pump （BSEP） in liver cells of obstructive jaundice rats, and to discuss the influence of FXR activation and endotoxin （ET） on the expression of BSEP. Methods Thirty-six healthy SD rats were randomly divided into sham operation group （Sham group）, common bile duet ligation （CBDL） group and bile reflow （BR） group. The FXR and BSEP transcription and protein levels of hepatocytes were measured with average optical density （AOD） and immunohistochemistry microscope in liver tissues from the three groups at each time point. Meanwhile, the levels of serum total bilirubin （TBIL）, total bile acid （TBA） and ET were examined with conventional methods. The relationships between FXR, TBA, ET and BSEP were analyzed by linear correlation analysis. Results The serum levels of TBIL, TBA and ET of rats in sham group at each time point after operation had no change （P〉0.05） the serum levels of TBIL, TBA and ET of rats in CBDL group after CBDL were significantly increased （P〈0.01）;the serum levels of TBIL, TBA and ET of rats in BR group after BR were gradually decreased, the levels of TBIL and TBA 7 d after BR had no difference compared with sham group （P〉0.05）, but the ET level was also higher than that in sham group （P〈0.05）. The expression levels of FXR in sham, CBDL and BR groups were increased gradually and slowly, but no significant differences were found among three groups （P〉 0.05）. The expression levels of BSEP in sham and BR groups tended to decrease with time; the expression level of BSEP in CBDL group was decreased firstly and then was increased, there was no significant differences compared with sham group （P〉 0.05）. Positive correlation was found between the genetic expression levels of FXR and TBA （r=0. 303, P〈 0.05）, while negative correlation was found between the expressions of FXR and BSEP （r= -0. 359, P〈 0.05）. The expression levels of BSEP and ET were also negatively correlated （r=-0. 412, P〈 0.01）. Conclusion The FXR level doesn＇t play a leading role in the expression of BSEP in the obstructive jaundice rats. The down- regulation of BSEP expression is mainly due to the expression level of ET.