| Background and objectives:Cardiovascular disease is the leading cause of mortality in type 2 diabetic mellitus(T2DM)patients.That the effects of T2DM on the heart and myocardial metabolism is studied to search of new interventions of diabetic cardiomyopathy(DCM)is of great significance.The purpose of this study was to investigate the changes of cardiac structure and myocardial metabolism in type 2 diabetic rats induced by high-fat diet and streptococcus,so as to provide certain experimental research data for clinical prevention and treatment of DCM,reversal of abnormal myocardial remodeling,delay and improvement of DCM pathological process and prognosis,and development of therapeutic drugs.Methods:Sprague Dawley male rats were fed a high fat diet(HFD)for a period of 28 days,with a single intraperitoneal injection of streptozotocin(STZ)on the 14th day at 30 mg/kg body weight.The model of HFD and STZ induced type-2 diabetes in rats was established.Normal control(NC)group,HFD group and STZ group were set as controls.On the 29th day,the rats were sacrificed to observe the indicators.General behavior,body weight,BMI,heart weight,and heart mass index were routinely observed.The levels of total cholesterol,triglyceride,glucose,insulin and glycosylated hemoglobin in blood,and the contents of glycogen and triglyceride in cardiac tissue were determined by biochemical methods.The structural changes of myocardial tissue in rats were observed by histopathological examination.The levels of glucose transporter 4(GLUT4)protein in heart tissue were analyzed by Western blotting.Results:1.Observation of general behavior and condition showed that the normal control(NC)rats showed the normal behavior of rats during the experimen,and the listlessness,dry and dull fur,and polydipsia,polyphagia,polyuria,and decreased weight gain increased BMI and heart weight were observed in type 2 diabetic(HFD+STZ)rats,and that compared with the STZ rats,there were statistically significant differences in weight gain,body mass index and heart weight in type 2 diabetic rats(P<0.05).2.Biochemical measurements showed that the levels serum total cholesterol,triglyceride,glucose and glycosylated hemoglobin(HbAA1c)in type 2 diabetic rats were significantly higher than those in NC rats(P<O.05),while insulin levels were lower than those in NC rats(P<0.05),and that compared with the HFD rats and the STZ rats,the serum levels of total cholesterol triglyceride,glucose and insulin were statistically significant differences in type 2 diabetic rats(P<0.05).3.Measurements of the content ofglycogen and triglyceride in myocardial tissue showed that the glycogen content in myocardial tissue of type 2 diabetic rats was significantly lower than that of NC rats(P<0.05),while the concentration of triglyceride in myocardial tissue was higher than that of NC rats(P<0.05),and that compared with the HFD rats and STZ rats,the glycogen content of the myocardial tissue was significantly decreased in type 2 diabetic rats,while the triglyceride concentration in the myocardial tissue of type 2 diabetic rats was significantly increased of type 2 diabetic rats(P<0.05).4.Histopathological studies showed the normal architecture of myocardium in normal control rats,and the dense focal fatty infiltration in myocardial cells in type 2 diabetic rats.5.Western blotting analysis of showed that the expression level of GLUT4 protein in the myocardial tissue of type 2 diabetic rats was significantly lower than that of the NC group(P<0.05),and that compared with the HFD rats and STZ rats,the expression level of GLUT4 protein in the myocardium of type 2 diabetic rats was significantly decreased(P<0.01).Conclusions:The present study results suggest that high fat feeding combined with STZ injection can induce diabetic cardiomyopathy in rats that show that the cardiac metabolic changes(decreased glucose and increased fat metabolism),heart weight increase and cardiac structure abnormalities,which suggest that this method can be used in type 2 diabetic heart disease mechanism research and drug screening. |
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