葡萄糖-6-磷酸酶和磷酸烯醇式丙酮酸羧激酶mRNA在梗阻性黄疸及胆道再通大鼠中的表达及意义

目的研究梗阻性黄疸及胆道再通大鼠肝脏葡萄糖-6-磷酸酶(G-6-P)和磷酸烯醇式丙酮酸羧激酶(PEPCK)mRNA表达的改变及意义,探讨梗阻性黄疸影响糖代谢的分子机制。方法 30只健康雄性大鼠随机分为5组:假手术组(A组)、梗阻性黄疸1周组(B组)、梗阻性黄疸2周组(C组)、梗阻性黄疸1周再通1周组(D组)、梗阻性黄疸2周再通1周组(E组)。检测各组动物血清丙氨酸氨基转移酶(ALT)、直接胆红素(DBIL),总胆红素(TBIL)水平;光镜观察肝脏形态学改变;采用RT-PCR方法检测大鼠肝脏葡萄糖-6-磷酸酶(G-6-P)和磷酸烯醇式丙酮酸羧激酶(PEPCK)mRNA的表达。结果胆道梗阻后,B、C两组血清TBIL、DBIL、ALT水平较A组明显升高,尤其是C组升高的更明显;光镜下可见B组和C组肝细胞肿胀,炎性细胞浸润,汇管区可见胆管增生,C组较B组除以上改变更加严重外,还可见典型的片状肝细胞坏死;B、C两组肝组织G-6-P、PEPCK的mRNA表达显著升高。相比,D、E两组血清TBIL、DBIL、ALT水平均分别低于B、C两组,肝脏形态改变也明显趋于正常,肝组织G-6-P、PEPCK的mRNA表达亦均低于B、C两组,且D组在血清、肝组织mRNA表达及光镜下肝细胞损伤方面与E组比较均降低。结论梗阻性黄疸模型形成后,大鼠肝脏分泌的胆汁排泄不畅形成淤积。肝脏中G-6-P、PEPCK mRNA表达开始增强且随梗阻时间延长其表达增强趋势更加明显,加强了糖异生的过程,可导致血糖浓度的升高。梗阻解除后,受损肝脏形态及肝功能开始恢复,肝脏G-6-P、PEPCKmRNA表达开始降低,及早解除梗阻,恢复越快。提示肝组织G-6-P、PEPCK的mRNA表达升高可能是梗阻性黄疸时糖代谢紊乱的主要原因之一。

Expression of mRNA of glucose 6 phosphatase and phosphoenolpyruvate carb-oxykinase kinase on rat models of obstruction jaundice and recannalization of biliary tract

Objective To investigate the expression and significance of mRNA of glucose-6-phosphatase(G-6-P) and phosphoenolpyruvate carboxykinase kinase(PEPCK) on rats with obstructive jaundice and recannalization of biliary tract,and to explore the molecular mechanisms of glucose metabolism affected by the obstructive jaundice.Methods Thirty healthy male Wistar rats were divided into five groups at random: group A(sham group),group B(obstructive jaundice one week group),group C(obstructive jaundice two weeks group),group D(obstructive jaundice one week and recanalization one week group),group E(obstructive jaundice two weeks and recanalization one week group).The levels of serum alanine aminotransferase(ALT),direct bilirubin(DBIL),and total bilirubin(TBIL) were measured.Morphological changes in hepatic tissues were observed under the light microscope.Expression levels of G-6-P and PEPCK mRNA in hepatic tissues were detected by RT-PCR.Results After obstruction,the levels of serum ALT,DBIL,TBIL in group B and C were increased significantly compared with group A,especially in group C.Pathological morphological has changed in hepatic tissues of group B and C,including swelling of hepatocytes,infiltration of inflammatory cells,and bile duct hyperplasia in portal area.Necroses of sheet liver cells were observed in group C which pathological change was more seriously and bile ducts and fibrous tissue proliferation were more obvious.Expression levels of mRNA of G-6-P and PEPCK in hepatic tissues of group B and C increased markedly compared with group A.Compared with group B and C,the levels of serum ALT,DBIL,TBIL were lower,expression levels of mRNA of G-6-P and PEPCK were lower,and morphological changes of liver were more normal in group D and E.Group D was less serious compared with group E in all aspects.Conclusion After the model of bile duct obstruction was constructed bile began to silting-up.With the biliary obstruction prolonged,the level of mRNA of G-6-P and PEPCK were increased in hepatic tissues time-dependently,and enhance the process of gluconeogenesis,lead to the elevation of blood sugar.However,the liver function and morphology began to recover time-dependently after bile flow restoration.The earlier remove obstruction,the faster recovery.Disturbance of glucose metabolism after obstructive jaundice may be the primary cause associated with the increase of expression levels of mRNA of G-6-P and PEPCK in hepatic tissues.