胆汁酸代谢主要调节核受体和相关基因在胆汁淤积孕鼠肝脏中的表达

Expression of FXR mRNA, PPAR alpha mRNA and bile acid metabolism related genes in intrahepatic cholestasis of pregnant rats

目的探讨法尼醇x受体（FXR）、过氧化物酶增殖体激活受体a（PPARa）与胆固醇7a羟化酶（CYP7A1）、胆固醇27a羟化酶（CYP27A1）、胆固醇12a羟化酶（CYP881）mRNA在妊娠期肝内胆汁淤积孕鼠肝脏中的表达及其意义。方法将60只清洁级SD大鼠自孕第13天均分为3组，对照组：皮下注射精制植物油2．0ml·kg-1·d-1未治疗组：皮下注射17—a-乙炔雌二醇1．25mg·kg-1·d-1治疗组：皮下注射17-a-乙炔雌二醇1．25mg·kg-1.d-1，孕第17天起给予非诺贝特50mg·kg-1·d-1灌胃。3组孕鼠分别于妊娠第13、17、21天断尾采血2ml检测血清生物化学指标，并于妊娠第21天处死，提取肝脏组织。应用酶联免疫吸附法检测3组孕鼠血清中的胆酸水平；用实时定量PCR技术检测各组PPARa、FXR、CYP7A1、CYP27A1、CYP881mRNA的表达量。多组间的比较用方差分析，多组的两两间比较用Student-Newman-Keuls法检验，两组数据间比较用t检验。结果妊娠第17天，对照组、未治疗组、治疗组的胆汁酸水平分别为（26．6±2．3）mol／L、（68．7±4．2）umol／L、（69．5±3．8）umol／L，未治疗组和治疗组胆汁酸水平与对照组比较，t值分别为2．516、2．642，P值均〈0．05，差异均有统计学意义。治疗组与未治疗组之间胆汁酸水平比较，t=1．835，P〉0．05，差异无统计学意义；妊娠第21天，对照组、未治疗组、治疗组胆汁酸水平分别为（27．1±3．2）umol／L、（69．4±3．7）umol／L、（48．5±4．8）umol／L，3组比较，F=7．81，P〈0．05，差异有统计学意义。对照组、未治疗组、治疗组中CYP7AI mRNA的相对表达量分别为0．75±0．02、1．55±0．03、1．25±0．01，FXRmRNA的相对表达量分别为1．25±0．03、1．75±0．02、1．65±0．05，CYP27A1mRNA的相对表达量分别为0．65±0．03、2．45±0．01、1．65±0．02，CYP8B1mRNA的相对表达量分别为1．50±0．02、2．15±0．01、1．75±0．03，PPARamRNA的相对表达量分别为1．45±0．02、0．85±0．02、1．35±0．01。CYP7A1、FXR、CYP27A1、CYP8B1mRNA在未治疗组中的表达量与对照组相比，口值分别为6．554、5．613、8．126和6．143，P值均〈0．05，差异均有统计学意义。未治疗组中PPARamRNA的表达量与对照组相比，q=6．126，P〈0．01，差异有统计学意义。治疗组中CYP27A1、PPARamRNA、CYP8B1mRNA水平与未治疗组相比，口值分别为6．346、7．231和5．892，P值均〈0．05，差异均有统计学意义。结论胆汁酸的合成与代谢调节机制存在障碍，是导致妊娠期肝内胆汁淤积症发生的原因之一，用PPARa的激动剂对其有一定疗效。

Objective To study the expressions of FXR, PPAR a and Bile acid metabolism related genes in intrahepatic cholestasis of pregnant rats. Methods 60 clean SD pregnant rats were selected and divided randomly into three groups. Since the 13th day of pregnancy rats in control group were injected subcutaneously with refined vegetable oil 2.0 mg. kg-1. d-1 Rats in no-treated group were injected subcutaneously with the 17- a -ethynylestradio （EE） 1.25 mg. kg-1. d-1 untill the 17th day. Those rat ih treated group were injected subcutaneously with the 17- a -ethynylestradio （EE） 1.25 mg. kg-1. d-1 tmtiU the 17th day and then were treated with fenofibrate for another four days untill the 21th day. All rats were killed at the 21th day and livers were collected for study. The levels of serum TBA were examined by ELISA. The mRNA expressions of PPAR a, FXR, CYP7A1, CYP27A1 and CYP8B 1 were examined by real-time PCR. Results （1） The levels of TBA were significantly higher in no-treated group （68.7 ± 4.2） umol/L and treated group （69.5 ± 3.8） umol/L compared with that of control group （26.6 ± 2.3） umol/L at the 17th day （P 〈 0.05） and no difference found between treated and no-treated groups （P 〉 0.05）. The levels of TBA were higher in notreated group （69.4 ± 3.7）umol/L and treated group （48.5 ± 4.8）/amol/L as compared to control group （27.1 ± 3.2） umol/L at the 21th day （P 〈 0.05）. The lever of TBA was significantly lower in Treated group compared with No-treated group （P 〈 0.05）. （2） The mRNA expressions of CYPTA1, FXR, CYP27A1 and CYP8B1 increased in No-treated group （1.55 ± 0.03, 1.75 ± 0.02, 2.45 ± 0.01, 2.15 ± 0.01, respectively） and were all higher as compared to control group （0.75 ± 0.02, 1.25 ± 0.03, 0.65 ± 0.03, 1.50 ± 0.02, respectively） （P 〈 0.05）. However, the mRNA expression of PPAR a decreased in No-treated group （0.85 ± 0.02） compared with control group （1.45 ± 0.02） （P 〈 0.05）. The mRNA expressions of CYP27A1, PPAR a and CYP8B1 increased in treated group （1.25 ± 0.01, 1.65 ± 0.05, 1.65 ± 0.02, respectively） and were all higher than that of control group （P 〈 0.05）. Conclusion Abnormal expressions of CYP7A1, FXR, CYP27A1, CYP8Bland PPAR a may play a role in pathogenesis of estrogen-induced intrahepatic eholestasis. Activator of PPAR a may be used as therapeutical drug for ICP.