| OBJECTIVES:To investigate relationship between peroxisome proliferator-activated receptorγ(PPARγ)and angiotensinⅡ(AngⅡ)in the process of myocardial fibrosis by observing the expression of PPARγand AngⅡin myocardial cells and microvasculature of diabetes rats.BACKGROUD:Diabetic cardiomyopathy(DCM),which is important specific myocardial disease, has always been accompanied by myocardial fibrosis and vascular damage,but the mechanism is uncertain in detail,many factors involve in the course.Now the AngⅡhas been regarded as a important factor.Researches of PPARγfocus on the onset of Diabetes mellitus(DM),but the role in DCM is uncertain.So we try to determine the expression and role of PPARγin myocardial fibrosis and it's relationship with AngⅡ.METHODS:1.Establishment of DM animal modelTwenty-seven male Wistar rats were randomly divided into 2 groups:control group(n=12)and DM group(n=15).Diabetes was induced by a single intraperitoneal injection of STZ(65 mg/kg body wt and dissolve in 0.1 mol/l citrate buffer,pH 4.2) in rats of DM group.Control rats received citrate buffer alone.One week after injection of STZ,fasting plasma glucose levels were measured,and rats with plasma glucose at least two times higher than 16.7mmol/L were thought of successful models. All rats were fed for 5 months after STZ or citrate buffer injections and had free access to standard rat diet and water.2.Radiate escape pestilence methodRadiate escape pestilence method was used to test the level of plasma AngⅡ.3.HE staining and Masson stainingHE staining was used to study the pathological changes and Masson staining was used to test the collagen in this study.4.ImmunohistochemistryImmunohistochemistry was used to detect the protein expression of PPARγand AngⅡ.RESULTS:1.At the end of the experiment,11 diabetic rats induced by STZ and 12 control rats survived.Glucose levels were significantly elevated in diabetic rats compared with control rats after STZ injection.2.The level of plasm AngⅡwas higher in DM group.3.HE staining and Masson stainingHE staining:The myocytes from the control group arranged regularly.The size of the nuclear was uniform.The staining cytoplasm was homogeneous.The myocytes from the DM group arranged irregularly.The nuclear was irregular and the interrupted myofibril arranged irregularly.Masson staining:After five months of diabetes,the cardiac collagen deposition was obviously enhanced in the DM groups compared with control groups,especially around the cardiac muscle cell and capillary.4.The expression of PPARγin DM group was higher than the control group, especially in the capillary endothelium and the myocardial cell.5.The expression of AngⅡin the cytoplasm of myocardial cells in DM group was higher than the control group.CONCULUTIONS:1.A DM animal model was established by 5 months period of STZ-induced diabetes in male Wistar rats,pathology methods determined the level of myocardial fibrosis. 2.The expression of PPARγand AngⅡin myocardial cells increased significantly in diabetes rats,and the level of plasm AngⅡwas higher in diabetes rats.They maybe correlate with each other in myocardial fibrosis.3.The expression of PPARγin capillary endothelium of diabetes rats increased significantly,maybe there is no relationship between them in capillary endothelium.
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