Protective Effect And Mechanisms Of Different Concentrations Of Adiponectin On Oxidative Stress After Ischemia-reperfusion In Diabatic Rats

PartⅠProtective effect of different concentrations of Adiponectin on Oxidative Stress after Ischemia-reperfusion in Diabatic RatsObjective To investigate the effect of different concentrations of adiponectin on oxidative stress after ischemia-reperfusion in diabatic rats and their dose-effect relationship. Moreover, choose the best concentrations of adiponectin to do further research.Methods Eighty healthy Sprague-Dawley rats were randomly divided into diabetics group(n=64) and non-diabetics group(n=16). Non-diabetics group received regular diet, however, diabetics diet group were given food in high fat and sugar. After eight weeks, rats which in diabetes group was induced by intraperitoneal injection of streptozotocin (STZ,35mg/Kg), meanwhile,non-diabetics rats serving as controls were injected the same volume of sodium citrate. After one week, we detected every group rats'fasting blood glucose in order to select the diabetics rats which fasting blood glucose were higher than 16.7mmol / L and the level of it maintain more than one week. Then rats in non-diabetics group were randomly divided into two groups: sham-operated group(CS) and ischemia-reperfusion group(CI/R). Rats in diabetic group were randomly reassigned into sham-operated group(DS), ischemia-reperfusion group(DI/R) ,low, middle and high concentrations of adiponectin(60,120,180 ng/g) groups, with 8 rats for each group. Sham group were suffered with sham operation. IR group were undergone the left anterior descending branch of coronary artery ischemia for 45 min and reperfused for 180min fusion. Rats in different adiponectin groups were infused with adiponectin for 30 min before ischemia-reperfusion. After reperfusion ,the left ventricular developed pressure(LVDP) and±dp/dtmax were recorded. At the end of experiment, the activities of total nitric oxide synthase (tNOS) and nitric oxide (NO)in the myocardium and superoxide dismutase (SOD) activity of serum were examined. At the same time, the infarct size was determined by using Evans blue and TTC double dye staining.Results (1)The weight of rats in diabetic groups was much lower and the blood glucose was much higher than that of non-diabetics group (P﹤0.05,P﹤0.01). (2) The cardiac function were significantly decreased in CI/R or CI/R group ,compare with CS or DS group.(3) Compare with CS or CI/R group, the level of total nitric oxide synthase and nitric oxide in the myocardium and serum superoxide dismutase was downregulated as well as cardiac function were significantly decreased in DS or DI/R group, whereas the cardiac infarct size was increased. (4)The infarct size was reduced in different adiponectin groups compared with I/R group,while the level of superoxide dismutase, total nitric oxide synthase and nitric oxide was significantly increased with a dose-dependent improvement of ischemia/reperfusion-induced myocardial contractile dysfunction and cardiac function was improved with dose-dependently.Conclusions :1.Adiponecin may protect hearts from ischemia-reperfusion injury in diabetics rats by reducing cardiac infarct size and improving myocardial contractile dysfunction. The molecular mechanism may involve preservation of total nitric oxide synthase ,nitric oxide and superoxide dismutase in serum and myocardial tissue, and protection of myocardium from ischemia-reperfusion-induced oxidative stress.2. Adiponecin may protect hearts from ischemia-reperfusion injury with dose-dependently in diabetics rats,and 180 ng/g dose seems as the best one.PartⅡAdiponect through PPARαsignaling pathway protect against the Ischemia—reperfusion injury and related mechanism analysis in Diabatic RatsObjective To investigate the effects of adiponectin(APN) on Ischemia-reperfusion injury in and do further research on its protective mechanism.Methods Eighty healthy Sprague-Dawley rats were randomly divided into diabetics group(n=16) and non-diabetics group(n=64).The rats in diabetics group and non-diabetics group were fed as the first part. Then rats in non-diabetics group were randomly divided into two groups: sham-operated group(CS) and ischemia-reperfusion group(CI/R). Rats in diabetic group were randomly reassigned into sham-operated group(DS), ischemia-reperfusion group(DI/R), adiponectin group, GW6471 group, adiponectin and GW6471 group ,with 8 rats for each group. Sham group were suffered with sham operation,however ,the other groups were taken surgery of ischemia-reperfusion which method were described in the first part. At the end of experiment, the activities of total nitric oxide synthase (tNOS) and nitric oxide (NO)in the myocardium and superoxide dismutase (SOD) activity of serum were examined. Meanwhile,the expression of caspase-3 and PPARαin the myocardium was examined by immunohistochemistry.Results (1)Compare with CS or DS group, the level of total nitric oxide synthase and serum superoxide dismutase in the myocardium was downregulated as well as the expression of PPARαin the myocardium were significantly decreased and the expression of caspase-3 in the myocardium were significantly increased in CI/R or CI/R group.(2) Compare with CS or CI/R group, the level of total nitric oxide synthase and serum superoxide dismutase in the myocardium was downregulated as well as the expression of PPARαin the myocardium were significantly decreased and the expression of caspase-3 in the myocardium were significantly increased in DS or DI/R group.(3)Opposite to DSI/R+GW6471 group,the level of total nitric oxide synthase and serum superoxide dismutase in the myocardium was downregulated as well as the expression of PPARαin the myocardium were significantly decreased and the expression of caspase-3 in the myocardium were significantly increased in APN group, Compare with DI/R group.(4) Compare with APN group, the level of total nitric oxide synthase and serum superoxide dismutase in the myocardium was downregulated as well as the expression of PPARαin the myocardium were significantly decreased and the expression of caspase-3 in the myocardium were significantly increased in DSI/R+APN+GW6471.Conclusions :1. Adiponecin may protect hearts from ischemia-reperfusion injury in diabetics rats by upregulated total nitric oxide synthase and superoxide dismutase in myocardial tissue, and increased expression of PPARαand decreased expression of caspase-3 ,in order to protect myocardium from ischemia-reperfusion-induced oxidative stress.2. Adiponectin can protect cardiomyocytes from the oxidative stress induced by ischemia-reperfusion through PPARαpathway.