Effects Of Rosiglitazone On The Activities Of AMPK In Skeletal Muscle Of High-fat Fed Rats

Background:With the development of society,there are more and more insulin resistance and type 2 diabetes patients.The effects of environment such as high-fat diet on insulin sensitivity are becoming more and more noticeably.Up to date,high-fat diet is a single risk factor leading to insulin resistance and type 2 diabetes,also named as "lipotoxocity",which is characterized by increased body weight,elevated plasma FFA levels and abnormal accumulation of fat in insulin target organs.AMPK,AMP-activated protein kinase,is a key regulator of intracellular fatty acid metabolism and insulin signaling.AMPK has been proved can increase insulin sensitivity by regulating not onlyβ-oxidation but also GLUT4.GluT4,glucose transport 4,is one protein of the glucose transport family who participates in the insulin signaling.The peroxisome proliferator-activated receptors(PPARs) are ligand-regulated transcriptors,and belong to the nuclear receptor superfamily.AMPK could increase theβ-oxidation of mice' skeletal muscle cells by activating the compound of PPARαand PPARγ.Ser/Thr phosphorylation of insulin receptor substrate(IRS) proteins is very important to insulin resistance.It is reported that AMPK can induce the Ser/Thr phosphorylation of IRS1.Rosiglitazone could ameliorate the insulin resistance but its mechanism has not completely been found now.Some think it can ameliorate insulin resistance by PPAR γand GLUT4,and others think it can activate AMPK.Then,could Rosiglitazone ameliorate the expression of AMPK,GLUT4,IRS1 and PPARγin our research? And is AMPK the key factor in Rosiglitazone's mechanism?Objectives:1.To observe the effects of chronic high-fat feeding on AMPKα1,AMPKα2,P-AMPK,T-AMPK,GLUT4,IRS1 and PPARγin skeletal muscle of rats.2.To investigate effects of Rosiglitazone on the activities of AMPKα1,AMPKα2,P-AMPK,T-AMPK,GLUT4,IRS1 and PPARγin skeletal muscle of high-fat fed rats.Methods:Male Wistar rats were divided into three groups randomly.They were control group(N,n=10),high-fat diet group(HF,n=10) and Rosiglitazone-treated group (HF+Ros,n=10).After high fat feeding for four months,rats in HF+Ros gourp were treated with Rosiglitazone at a dose of 1mg/(kg·d) by oral for one month.Skeletal muscles of all animals were gained for further analysis.The mRNA levels of AMPKα1,AMPKα2 and GLUT4 were tested using Real time PCR.While the mRNA levels of IRS1 and PPARγwere measured using RT-PCR.And the protein levels of total AMPK,P-AMPK and GLUT4 of were tested by Western blot.Results:1.Compared with controls,the mRNA levels of AMPKα2,GLUT4 and PPARγwere reduced,and the protein expression of total AMPK,P-AMPK and GLUT4 were also decreased,respectively,.in the rats with high-fat diet.But no testing mRNA changes of both AMPKα1 and IRS1.2.Compared with HF group,Rosiglitazone could increase the mRNA levels of GLUT4,PPARγand IRS1,and also enhanced the protein expression of P-AMPK,GLUT4.But there are not changes in AMPKα1,AMPKα2 and T-AMPK.Conclusions:1.There are changes in the mRNA levels of AMPKα2,GLUT4,PPARγand total AMPK,P-AMPK in the rats with high-fat diet.2.Rosiglitazone could increase the expression of GLUT4,PPARγ,IRS1,P-AMPK and GLUT4 which suggests that it could ameliorate the insulin resistance.