| Objective:1.To verify the regularity of NGF expression in myocardium of diabetic rats.To explore the feasibility of using adeno-associated virus(AAV)as vector to introduce exogenous NGF gene into the heart of diabetic rats to reverse the decrease of NGF expression.2.To compare the degree of injury,the level of myocardial apoptosis,and the occurrence of arrhythmias during myocardial ischemia reperfusion(I/R)in diabetic and nondiabetic rats.To investigate whether aav-mediated NGF gene transduction in myocardium can reduce the worsening effect of diabetes on myocardial I/R injury and to elucidate its potential mechanism.Methods:1.AAV-mediated nerve growth factor gene transduction in a diabetic rat model.8 week old healthy male SD rats weighing 230 g to 250 g.Rats were divided into normal control(Control)group,diabetic(DM)group,diabetic empty virus(DA)group and diabetic AAVNGF transduction group(DN)group by random number table method,with 18 rats in each group.After one week of adaptive feeding,except for the other 3 groups of the Control group: 1% STZ solution was intraperitoneally injected at 50 mg/kg.Blood glucose was measured 24 hours after administration,and then every 24 hours for a total of 7 measurements.Modeling criteria: Each blood glucose value is greater than 16.7 mmol / L.Control group: rats fasted(not allowed to drink water)for 24 hours.Two weeks after the modelling of diabetic rats,the rats were injected with myocardial points in the open chest.The DA group and the DM group were injected with the corresponding AAV virus solution,and the control group and the DM group were injected with the same volume of PBS solution.After 4 weeks of gene transduction,the expression of GFP in the left ventricular frozen section of the genetransduced rat was observed by fluorescence microscopy.The expression of NGF in the left ventricle of each group was detected by ELISA.2.Effect of nerve growth factor gene transduction on myocardial ischemia/reperfusion injury in diabetic rats.Four weeks after gene transduction,the I/R injury model was established by ligation of the left anterior descending coronary artery for 30 minutes and loosening for 120 minutes.The content of cardiac troponin I and myocardial caspase-3 in ischemic area were detected by ELISA.ECG recorded ventricular premature contraction,ventricular tachycardia,and ventricular fibrillation during I/R,and analyzed the incidence,number of episodes,and duration.Results:1.Compared with the Control group,the blood glucose levels of the DM,DA,and DN groups increased significantly from the second day of modeling(all P < 0.01),reaching the standard of the diabetic animal model,and the hyperglycemia state continued until the end of the experiment.2.After 4 weeks of gene transduction,green fluorescence was observed in the left ventricle of the DA and DN groups under fluorescence microscope.3.Compared with the Control group,the expression of NGF in the left ventricular myocardium of the DM and DA groups was lower(P < 0.05).Compared with the DM group,the expression of NGF in the left ventricle of the DN group was higher(P < 0.05).4.After myocardial ischemia for 30 min and reperfusion for 120 min,myocardial troponin I was significantly more in the DM,DA,and DN groups than in the Control group(all P < 0.05).Compared with the Control group,the expression of caspase-3 in the ischemic area of the DM and DA groups was more(both P < 0.05).Compared with the DM group,there was less active caspase-3 in the ischemic area of the DN group(P < 0.01).5.During I/R,compared with the Control group,the average number of ventricular premature contractions and ventricular tachycardia increased in the DM and DA groups(all P < 0.05),and the mean duration of ventricular tachycardia and ventricular fibrillation was prolonged.(all P < 0.05).Compared with the DM group,the mean number of ventricular premature contractions and ventricular tachycardia decreased in the DN group(both P < 0.05),and the mean duration of ventricular tachycardia and ventricular fibrillation was shortened(both P < 0.05).Conclusion:1.AAV mediated cardiac NGF gene transduction can reverse the decrease of cardiac NGF expression in STZ induced type 1 diabetic rats.2.Compared with normal rats,diabetic rats have more active apoptotic responses during myocardial I/R,and lethal arrhythmia attacks are more frequent and last longer.3.AAV-mediated myocardial NGF gene transduction inhibits myocardial NGF expression in type 1 diabetic rats induced by STZ,inhibits cardiomyocyte apoptosis in rat myocardial I/R injury,and reduces the occurrence of lethal arrhythmia. |
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