Effect Of Hydrogen Sulfide On Cardiomyocyte Apoptosis Induced By Acute Myocardial Ischemic Injury And Its Effect Mechanisms

Part one Changes of glycogen synthase kinase-3?/?-catenin protein expressions in acute myocardial ischemic ratsObjective: To observe the changes of protein expressions of GSK-3? and ?-catenin in acute myocardial ischemic heart tissues in rats.Methods:1 Forty male Sprague-Dawley rats,weighing 250-290 g,were randomly assigned into five groups(n=8): i)sham group,ii)ischemia 2h group,iii)ischemia 3h group,iv)ischemia 6h group,v)ischemia 9h group.The rats were subjected to ligation of the anterior descending artery resulting in acute myocardial ischemic injury.The rats were anesthetized,and the electrocardiogram was recorded.Sham rats underwent the same procedure except the suture was passed under the coronary artery and then removed.2 The mean arterial pressure(MAP),left ventricular developed pressure(LVDP),left ventricular end-diastolic pressure(LVEDP),and rate of contraction and relaxation(dp/dtmax and dp/dtmin)were respectively recorded to evaluate the cardiac function.3 The activity of lactate dehydrogenase(LDH)in serum was determined.4 The morphological change in the myocardium was analyzed in hematoxylin and eosin(H&E)staining.5 The expressions of phosphorylated(p-)GSK-3?,total(t-)GSK-3?,and ?-catenin were determined by western blot.Results: 1 Compared with those of the sham group,MAP,LVDP,dp/dtmax and dp/dtmin were significantly decreased and LVEDP was increased at 3h,6h,and 9h after ischemia(P<0.01).2 Compared with that of the sham group,the activity of LDH in serum was increased at 3h,6h,and 9h after ischemia(P<0.01).3 Compared with that of the sham group,the disorganization of cell structures,loss of cell-cell adherence between cardiomyocytes and abnormally shaped cell nuclei were demonstrated at 6h and 9h after ischemia.4 There was no significant difference between groups in total-GSK-3? expression by western blot analysis,although the p-GSK-3? amount,p-GSK-3?/t-GSK-3? ratio,and the ?-catenin were significantly decreased at 3h,6h,and 9h after ischemia compared with that of the sham group(P<0.01).Part two Effects of hydrogen sulfide on acute myocardial ischemia-induced apoptosis via glycogen synthase kinase-3?/?-catenin signaling pathwayObjective: To evaluate the cardioprotective effects of hydrogen sulfide(H2S)against acute myocardial ischemia and explore its possible mechanisms.Methods:1 Fifty-six male Sprague-Dawley rats,weighing 250-290 g,were randomly divided into seven groups(n=8).i)sham group,ii)acute myocardial ischemia(AMI)group,iii)-v)ischemia groups treated with low-,medium-,high-dose NaHS(AMI+low-,medium-,high-dose NaHS),vi)ischemia group treated with SB216763(AMI+SB),and vii)ischemia group treated with vehicle(AMI+vehicle).The rats were subjected to ligation of the anterior descending artery resulting in acute myocardial ischemic injury.Sham rats underwent the same procedure except the suture was passed under the coronary artery and then removed.NaHS(0.78,1.56,3.12 mg/kg body weight,intraperitoneally)was respectively administrated in AMI+low-,medium-,high-dose NaHS group rats.SB216763(0.6mg/kg,dissolved in 1% dimethylsulfoxide,intravenous)was administrated in AMI + SB group rats,1%DMSO(2 ml/kg,intravenous)was administrated in AMI + vehicle group rats.2 The mean arterial pressure(MAP),left ventricular developed pressure(LVDP),left ventricular end-diastolic pressure(LVEDP),and rate of contraction and relaxation(dp/dtmax and dp/dtmin)were respectively recorded to evaluate the cardiac function.3 The activity of lactate dehydrogenase(LDH)in serum was determined.4 The morphological change in the myocardium was analyzed in hematoxylin and eosin(H&E)staining.5 The TUNEL assay was used to evaluate the apoptosis of cardiomyocytes.6 The expressions of p-GSK-3?,t-GSK-3?,?-catenin,Bax,and Bcl-2 were determined by western blot and immunohistochemical staining.Results: 1 Compared with those of the sham group,MAP,LVDP,dp/dtmax and dp/dtmin were significantly decreased,and LVEDP was increased in AMI group rats(P<0.01).Compared with those of the AMI group rats,MAP,LVDP,dp/dtmax and dp/dtmin were significantly increased,and LVEDP was decreased in AMI+low-,medium-,and high-dose NaHS group rats(P<0.05 or P<0.01).2 Compared with that of the sham group,the concentration of LDH in serum was significantly increased in AMI group rats(P<0.01).Compared with that of the AMI group,the activity of LDH was significantly decreased in AMI+low-,medium-,and high-dose NaHS group rats(P<0.05 or P<0.01).3 Compared with that of the sham group,the disorganization of cell structures,loss of cell-cell adherence between cardiomyocytes and abnormally shaped cell nuclei were demonstrated in AMI group rats.Compared with that of the AMI group,the cardiomyocyte necrosis,edema and inflammatory cell infiltration into the myocardium were significantly decreased in AMI+low-,medium-,and high-dose NaHS group rats.4 Compared with that of the sham group,the expression of Bcl-2 was significantly decreased,and the expression of Bax and Bax/Bcl-2 ratio were significantly increased in AMI group rats(P<0.01).Compared with that of the AMI group,the expression of Bax and Bax/Bcl-2 ratio were significantly decreased,and the expression of Bcl-2 was significantly increased in AMI+low-,medium-,and high-dose NaHS group rats(P<0.05 or P<0.01).Moreover,compared with that of the sham group,a number of TUNEL-cells were exhibited in AMI group rats(P<0.01).Compared with that of the AMI group,the TUNEL-positive cardiac cells were significantly decreased in AMI+low-,medium-,and high-dose NaHS group rats(P<0.05 or P<0.01).5 There was no significant difference between groups in total-GSK-3? expression by western blot analysis.Compared with that of the sham group,the expression of p-GSK-3?,p-GSK-3?/t-GSK-3?,and ?-catenin were significantly decreased in AMI group rats(P<0.01).Compared with that of the AMI group,the expression of Bax and Bax/Bcl-2 ratio were significantly decreased,and the expression of p-GSK-3?,p-GSK-3?/t-GSK-3?,and ?-catenin were significantly increased in AMI+low-,medium-,and high-dose NaHS groups rats(P<0.05 or P<0.01).6 Compared with that of the AMI +vehicle group,the phosphorylation of GSK-3?,p-GSK-3?/t-GSK-3? ratio,and the content of ?-catenin were significantly increased in AMI+SB group rats(P<0.01).In addition,the MAP,LVDP,dp/dtmax,and dp/dtmin were significantly increased,and the LVEDP,serum LDH activity,Bax/Bcl-2 ratio,and apoptotic cells were significantly decreased in AMI+SB group compared with that of the AMI control group rats(P<0.01).Conclusions:1 The expressions of p-GSK-3? and ?-catenin were decreased in the acute myocardial ischemic rats.2 H2 S could exerte cardioprotective effects against acute myocardial ischemic injury-induced apoptosis.3 It could be concluded that H2 S exertes cardioprotective effects against acute myocardial ischemic injury-induced apoptosis via the glycogen synthase kinase-3?/?-catenin signaling pathway.