| Objective: Cardiovascular disease is the major death cause of diabetes mellitus and is responsible for 80% of deaths among diabetic patients. Diabetic cardiomyopathy, Independent of the severity of coronary artery disease, is one of the most common complications of diabetes. It is histologically characterized by overaccumulation of extracellular matrix and interstitial tissue reconstruction, displaying myocardial hypertrophy and myocardial fibrosis. It's clinical character is diastolic dysfunction in earlier period and systolic dysfunction advanced stage. Many researches find that metabolic disturbance leading by hyperglycemia is initiating agent. In addition, cell function change and many cell factor are all responsible for occurrence and development of diabetic cardiomyopathy. It is difficult to research and early intervention because of it's complicated causes of disease and specific pathophysiological diagnosis.This research is to aim at three objective: first, It is to establish type2 diabetic cardiomyopathy of rats. Second, It is to approach myocardium tissue ultrastructure change of animal diabetic cardiomyopathy model.Third, to finding the effect of a new inducing fibrosis growth factor-connective tissue growth factor on diabetic cardiomyopathy and reciprocal influence with AngⅡand transforming growth factorβso that clarity pathogenesy of diabetic cardiomyopathy and find effective prevention and a new cure methord.Methods:1.induction of type2 diabetic cardiomyopathy in ratsChoosing healthy male Wistar rats 45 with 180±20g body weight .After adaptive feeding for two weeks, rats were randomly divided into two groups: control group(n=15) and experiment group(n=30). Two groups were respectively fed common feeder and fat-high feeder (with 10% lard stearin, 20% cane sugar, 2.5% cholesterin, 1% cholate) for 8 weeks. Detecting fasting blood glucose, fasting insulin , triglyeride and total cholesterol and evaluating insulin resistance index according of homeostasis model assessment index. The rats of experiment group received a single intraperitoneal injection of STZ dissolved in 0.1mol/L sodium citrate (pH4.2) at a dose of 25mg/kg body weight /a day after emerging insulin resistance. The rats of control group only received an injection of the same volume of 0.1mol/L sodium citrate. Two weeks later, detecting fasting blood glucose, the model of diabetes was considered to be successful when the fasting blood glucose was≥16.7mmol/L. The type2 diabetes rats model were randomly divided into two groups again: diabetic cardiomyopathy group and Lotensin treatment group. Three rats were continued fed with former feeder. 2.detection of blood glucose,insulin and blood fatDrawing rats, fasting venous blood from angular vein, then blood plasma was separated. The levels of blood glucose and insulin were evaluated by glucose oxidase method and radioimmunity assay respectively. Degree of insulin resistance and Insulin Sensitivity Index were evaluated with Homeoestasis Model Assessment. Each terms rats were subjected to an oral glucose tolerance test (OGTT) at the end of the experiment.Triglycerid, total cholesterole and highdensity lipoprotein- cholesterole were evaluated by colorimetric method. Lower density lipoprotein-cholesterole was calculated according of Friedewald formula ( LDL-C=TC-HDL-TG/2.2 ) .Cu+ colorimetric method was used to detect FFAs.3.The immunohistochemistry expression of CTGF and TGF-β1 in myocardium interstitial tissue of three group ratsThe type2 diabetes rats model was induced by fat-high feeder add small dose STZ of intraperitoneal injection. Then diabetic model rats were randomly divided into two groups: type2 diabetic cardiomyopathy group,Lotensin treatment group. The rats of treatment group received a single intragastric administration of Lotensin dissolved in distilled water at a dose of 10mg/kg body weight/a day. The rats of control group and diabetes group only received an injection of the same volume distilled water. After 8 weeks, rats was put to death to have partial heart tissue fixed in 4% formaldehydum and embeded with paraffin for morphology examination and immunohistoche- mistry. (Partial tissue was fixed in 4% glutaraldehyde used to electron microscope examination). Different expression levels of CTGF and TGF-β1 in three teams were evaluated by immu- nohistochemistry.4.Myocardial cell morphology examinationPreparing rats heart tissue sections with routine method used to HE and VG staining. Tissue fine structure was observed by transmission electron microscope.5.Statistical treatmentAll data were handled with SPSS12.0 software. Measurem- ent data were analysis by M±SD. Interclass difference was compare with T analysis and over two sets with one-factor analysis of variance. P<0.05 show significant differences, P<0.01 show extreme significant differences.Results:1.Variation of body weightAt the experiment beginning, the body weight of three groups rats were no difference. After 8 weeks, compare with normal control, the body weight of the rats of experiment group were much higher than control group(p<0.01). After succeeding in building type2 diabetic model, the body weight of diabetic cardiomyopathy rats and Lotensin treatment group grow more slowly than control group. At the and of experiment, the body weight of diabetic cardiomyopathy rats and Lotensin treatment group were higher than normal control group( p<0.05).2.Changes of blood glucose, blood insulin and blood fat At the end ot 8 weeks, the fasting blood glucose of the control and experiment group were no difference, but the insulin degree of experiment group was higher than control group(P<0.01),ISI have a great low level. This show experiment rats have insulin resistant. The TC,TG,LDL and FFA of experiment group was higher than control group.Injection of STZ two weeks later, the blood glucose of diabetic cardiomyopathy group and Lotensin treatment group is higher than control group, fasting insulin begin to lessen but is higher than control group(p<0.05). The TC,TG,LDL and FFA of experiment group were also higher.At the end of experiment, the fasting blood glucose and insulin of the diabetic cardiomyopathy group and Lotensin treatment group were higher than control group.The TC,TG,LDL and FFA of experiment group was higher than control group (P<0.01).3.Morphologic change, ultrastructure and collagen of myocardiumAt the end, comparing with normal control rats, the myocardial cell of diabetic cardiomyopathy rats was raritas,swell and more collagen in interstitial tissue. Muscular fibril become lessen and disord. Chondriosome is swell and internal structure vanish. Myocardical cell ultrastructure was damaged severly. Treatment group was obviously improved but can not completely cure.4.Expression of CTGF and TGF-β1 in rats myocardium Expression of CTGF: the interstitial tissue of normal group were seen a few pallide-flavens substance. The interstitial tissue of diabetic cardiomyopathy rats were seen lots of buffy substance. Buffy substance of treatment group lessen.Expression of TGF-β1: Myocardical cell cytoplasm of normal group were seen a few yellow substance. The diabetic cardiomyopathy rats were seen lots of buffy substance in cytoplasm. Buffy substance of treatment group lessen.Conclusions:1 Male Wistar rat was fed with a diet enriched with sucrose(10%),triglyceride(10%) and cholesterol (5%) to induce insulin resistance, and after two month on the diet streptozotion(STZ,30mg/kg) was injected in traperitoneally to induce hyperglycemia. This rat model simulates human type2 diabetes in moderate hyperglycemia, hypertension, dyslipidemia and insulin resistance.2 After Lotensin treatment, the higher expression of CTGF and TGF-β1 in rats with diabetic cardiomyopathy was decreased obviously and myocardium morphology also better. This changes show that Lotensin have protection function.3 The blood fat of treatment group and diabetes group have no difference. This show the protection of Lotensin is independent of lowering blood fat. It is likely to function by means of lowering CTGF and TGF-β1expression.
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