Study On CAV3 Transgenic Therapy For Diabetic Cardiomyopathy In Rats

Objective:Diabetes mellitus(DM)is a metabolic disease characterized by hyperglycemia caused by absolute or relative deficiency of insulin.Some patients with DM may develop diabetic cardiomyopathy(DCM),which is mainly characterized by myocardial metabolism,structural and functional disorders,and even heart failure.DCM is an important cause of heart failure and sudden death in DM.At present,there is no treatment for myocardial treatment for DCM,mainly for DM to control blood sugar and blood pressure,and regulate blood lipids and other symptomatic drugs.Caveolin-3(CAV3)is a specific protein on the membrane microcapsules of muscle cells(skeletal muscle cells,cardiomyocytes and smooth muscle cells).It is closely related to cardiac growth and myocardial cell physiological functions,and regulates insulin receptor(IR).,G protein and other related signaling pathways,especially regulating insulin receptor-related signaling pathways.High glucose stimulates skeletal muscle cells to increase the expression of CAV3,which can increase the uptake and utilization of glucose by cells,and promote the growth,metabolism and proliferation of cells.In high glucose cultured cardiomyocytes,the change of CAV3 protein with time increased first and then decreased.The expression of CAV3 in the heart of rats with advanced heart failure was significantly decreased.We hypothesized that in early diabetic rats,elevated blood glucose stimulated the compensatory increase of myocardial CAV3 protein,and the decrease of late CAV3 accompanied by myocardial metabolism,structural and cardiac insufficiency decompensation.Therefore,we intend to observe changes in CAV3 protein in rat DCM myocardium,and try to genetically increase the expression of CAV3 to rescue and treat DCM.Methods:A rat model of type 1 diabetes mellitus(T1DM)was established by intraperitoneal injection of streptozotocin(STZ)in a large dose(55 mg/kg),using a high-sugar and high-fat diet combined with low-dose(30 mg/Kg)STZ established a rat model of type 2 diabetes mellitus(T2DM).Echocardiography continuously monitored cardiac function in DM rats.When the cardiac function was significantly reduced and the expression of myocardial CAV3 was decreased,CAV3 packaged with adeno-associated virus was injected into the diabetic rats through the tail vein for transgenic therapy.Body weight,blood glucose,blood lipids and plasma insulin levels were measured regularly during the experiment.The changes of DCM structure were evaluated by transmission electron microscopy and histopathological examination.The myocardial damage was reflected by plasma myocardial enzyme,and the myocardial state was reflected by myocardial antioxidant index and metabolic enzyme index.Cardiac function changes in rat DCM were determined by echocardiographic examination.Results1.The expression of CAV3 protein in the early stage of T1DM(4-8 weeks)increased gradually with the course of disease,and began to decrease in the middle stage(12 weeks),and then reached the lowest stage(20 weeks).The expression of CAV3 protein was significantly decreased in the middle stage(12 weeks)of rat T2DM.2.Cardiac function began to decrease significantly in the middle of T1DM and T2DM(12 weeks and 14 weeks).The decline in T1DM(20 weeks)was most pronounced in rats.3.In the middle stage of T1DM and T2DM(12 weeks and 14 weeks),the body weight decreased,blood sugar,blood lipids and myocardial enzymes increased significantly,and obvious insulin resistance appeared.Myocardial histopathological sections showed myocardial muscle fiber disorder,myocardial hypertrophy,inflammatory cell infiltration,myocardial tissue transmission electron microscopy showed mitochondrial swelling,decreased myocardial antioxidant capacity,increased myocardial metabolic enzymes,and decreased left ventricular function.4.After the transgenic CAV3 transgene in rat T1DM(12 weeks),the detection of myocardial WB and immunohistochemistry showed that CAV3 and glucose transporter 4(GLUT4)were significantly increased in myocardial expression,and WB showed insulin receptor ?(IR?),p-AKT/AKT.The expression level of p-GSK3?/GSK3? was also significantly increased.The left ventricular function was significantly improved,the myocardial-derived plasma creatine phosphokinase isoenzyme(CK-MB)was significantly reduced,the myocardial pathological structure and ultrastructure were improved,the myocardial antioxidant capacity was improved,and the immediate blood glucose level was not significantly changed.Cardiac function was also significantly improved after transgenic T2DM in rats,and both CK-MB and LDH were significantly decreased.5.After the transfection of CAV3 in the late stage of T1DM(20 weeks),the expression of CAV3 in myocardium was not significantly increased,and blood glucose,blood lipids and left ventricular function were not improved,but LDH has been significantly reduced.Conclusions1.Transgenic T1DM in rats(12 weeks)transgenic gene increased the expression of CAV3 protein in DCM rats,improved myocardial metabolism through GLUT4 and related PI3K/AKT signaling pathway,improved myocardial antioxidant capacity,and effectively repaired myocardial structure and cardiac function of DCM.The CAV3 transgene may be an effective treatment for DCM.2.Transgenic T2DM in rats(14 weeks)significantly improved cardiac function and significantly decreased CK-MB and LDH in DCM rats.3.The late(20 weeks)transgene of rat T1DM did not enable the transfected CAV3 to be effectively expressed in the myocardium,and could not exert its therapeutic effect,so it did not improve the cardiac function of rats with advanced diabetes.