非诺贝特及二甲双胍对非酒精性脂肪性肝病大鼠的干预作用及机制

The effects and mechanism of Fenofibrate and Metformin on nonalcoholic fatty liver disease in rats

目的比较过氧化物酶体增殖物激活受体α(PPARα)和腺苷一磷酸激活蛋白激酶α(AMPKα)的配体非诺贝特和二甲双胍对非酒精性脂肪性肝病(NAFLD)大鼠的干预作用并探讨其可能机制。方法 Wistar大鼠分别予正常饲料喂养(对照组,Control)和高脂饮食喂养16周后又分为高脂饮食组(HF)、高脂饮食加非诺贝特组(FF)及高脂饮食加二甲双胍组(Met)每组12只,并继续喂养4周后检测:1测血清甘油三酯(TG)、胆固醇(CHO)、低密度脂蛋白胆固醇(LDL-C)、谷丙转氨酶(ALT)、空腹血糖、胰岛素含量。2取肝组织测TG含量。3肝组织HE染色观察病理形态。4RT-PCR及Western-blot分别检测肝脏AMPKα1和2、PPARα、乙酰辅酶A羧化酶(ACC)、肉碱酯酰转移酶1(CPT-1)的mRNA及蛋白含量。5测肝组织丙二醛(MDA)、超氧化物歧化酶(SOD)含量。结果 1高脂饮食可升高血脂质谱、ALT和空腹血糖(P<0.05),非诺贝特及二甲双胍均能改善血脂(P<0.05),但非诺贝特不能纠正ALT、空腹血糖(P>0.05),而二甲双胍可改善上述指标(P<0.05)。2高脂饮食可使肝脏TG含量增加(P<0.05),非诺贝特不能纠正高脂饮食诱导的肝脏TG增加(P>0.05),而二甲双胍则使其降低(P<0.05)。3高脂饮食组肝脏病理学形态提示NAFLD改变;给予非诺贝特病理学较单纯高脂饮食组形态无改善,而二甲双胍病理学形态有所改善。4高脂饮食组AMPKα1、CPT-1的蛋白及mRNA表达下降、PPARα和ACC蛋白及mRNA表达升高(P<0.05);非诺贝特显著升高PPARα及CPT-1蛋白及mRNA表达(P<0.05),而二甲双胍以升高AMPK及恢复ACC的蛋白及mRNA表达为主(P<0.05)。5高脂饮食组肝组织MDA含量增加、SOD含量下降(P<0.05),非诺贝特使得下降的MDA回升(P<0.05),二甲双胍降低则进一步降低MDA、升高SOD(P<0.05)。结论非诺贝特虽能降低血脂,但不能改善NAFLD,而二甲双胍可改善NAFLD,可能与非诺贝特过度激活PPARα导致脂质过氧化损伤,而二甲双胍则以激活AMPK为主,导致胰岛素抵抗改善、脂肪合成下降、分解适度增加有关。

Objective To compare the different effects on NAFLD of Metformin and fenofibrate,the ligand of PPARaαand AMPKαrespectively.Methods Wistar rats received normal diet（control group）and high fat diet.After 16 weeks,the latter group was divided into high diet group（HF）,high fat diet pulse fenofibrate group（FF）,and high fat diet pulse metformin group（Met）.All rats were feed for the next 4weeks.TG,CHO,LDL-C,ALT,fast glucose and insulin were measured.TG in hepatic tissue was detected.The pathological change of hepatic tissue was observed with HE staining.The mRNA and protein contents of AMPKα1,2,PPARα,ACC and CPT-1were detected with RT-PCR and Western-blot.5 The contents of MDA and SOD in hepatic tissue were detected.Results High fat diet would elevate blood lipid,ALT,and fasting glucose（P〈0.05）,while fenofibrate and metformin could correct the change of blood lipid induced by high fat diet（P〈0.05）.Metfirmin could improve blood glucose and ALT,but fenofibrate could not（P〈0.05）.High fat diet elevated liver TG.Fenofibrate could not correct the increased liver TG（P〈0.05）,but metformin could（P〈0.05）.High fat diet induced the liver steatosis.Metformin improved liver pathology morphology,while fenofibrate could not.The mRNA and protein expression of AMPKα1and CPT-1were decreased in High fat diet group（P〈0.05）,while that of PPARαand ACC were increased（P〈0.05）.Fenofibrate raised mRNA and protein of PPARαand CPT-1（P〈0.05）,while metformin mainly rised AMPK and restored the ACC protein and mRNA expression（P〈0.05）.High fat diet could elevate MDA content in liver and decline SOD（P〈0.05）.Fenofibrate raised MDA further,while metformin reduced MDA and raised SOD（P〈0.05）.Conclusions Fenofibrtae could reduced blood lipid,but cannot improved NAFLD,while metformin could improve NAFLD,which may be concerned with the oxidative damage induced by excessive activation of PPARαby fenofibrate.Metformin was mainly activating AMPK,resulting in an improvement of insulin resistance,and a decline of fat synthesis,and a modest increase of fat decomposition.