The Phosphorylation Of GSK3β Mediated Atorvastatin Calcium Postconditioning Reduce Myocardial Ischemia-reperfusion Injury In Streptozotocin-induced Type2diabetic Rats

Background Diabetes is an independent risk factor for ischemic myocardium disease,and many epidemiological data or laboratory studies also showed that diabetessignificantly aggravated myocardial ischemia/reperfusion injury and blunted theregular protective effects.Objective1) To develop a rat model of type2diabetic which close to clinical practice;2) To observe whether atorvastatin calcium postconditioning alleviates myocardialischemia-reperfusion injury on type2diabetic rats, test the changes of p-GSK3β incardiomyocytes, and explore the potential proximate mechanism.Methods1)1%STZ was injected into the abdominal cavity after the high fat andhigh sugar diet to create SD rats’ model of type2diabetic mellitus, then monitor ofbody weight and blood sugar regularly, and detect the serum lipids, includingtriglyceride and total cholesterol.2) Diabetic rats were randomly divided into sixgroups, and age-matched male non-diabetic SD rats were randomly divided into twogroups. Non-diabetic rats were divided into sham group and I/R group. Diabetic ratsweredivided into: sham group, I/R group, TDZD-8+optima dose atorvastatin calciumgroup, different dosage of atorvastatin calcium postconditioning group（s1or2mg/kg）and the solvent(DMSO) group. Sham operation (sham) groupistreated with open chestoperation but without myocardial ischemia/reperfusion as controls; Ischemiareperfusion injury (I/R) groupunderwent40min ischemia and180min reperfusion inleft anterior descending coronary territorywith no other interventions; different druginterventions werepushed in femoral vein slowly before reperfusion. The serum cTnIand HSP70were determined by ELISA; myocardial infarct size and histology and morpholog change were observed; the distribution ofp-GSK3β in cardiomyocytes wasshown by immunohistochemistry; myocardial expression of GSK3β, p-GSK3β,HSF-1were determined by western blot.Results1) Compared with the non-diabetic rats, the fasting blood glucose, the serumtriglyceride, total cholesterol of diabetic rats were increased, while the body weightdid not fall significantly in the first three weeks after inject STZ.2)①There were nostatistical significance of the myocardial infarction size between the non-diabetic ratsand diabetic rats, while in diabetic rats, the level of serum cTnI, morphological lesionof myocardial cell, and the level of GSK3β were higher than non-diabeticrats(P<0.05).②Compared with I/R group, the myocardial infarction size decreased,the levelof cTnIdecreased,and the morphological lesion was attenuated in theTDZD-8+optima dose atorvastatin calcium group and different-dosage-of atorvastatincalcium postconditioning groups.③Compared with atorvastatin calciumpostconditioning group (1mg/kg), the atorvastatin calcium postconditioning group(2mg/kg) could further alleviate morphological lesion, reduce myocardial infarct size,reduce the lever of cTnI and increase the level of p-GSK3β (P<0.05).④There wereno significant differences in the level of myocardial infarction size, cTnI,morphological lesion of myocardial cell, as well as the level of p-GSK3β betweenTDZD-8+optima dose atorvastatin calcium group and atorvastatin calcium group(2mg/kg)(P>0.05).⑤The changes of HSF-1and the serum HSP70were the samewith p-GSK3β in cardiomyocytes.⑥p-GSK3β was located in the plasma and nucleusof cardiomyocytes according to the result of immunohistochemistry analysis.Conclusion1) A relatively reliable animal model for type2diabetes could be set upby the high-fat and high-sugar diet together with intraperitoneal injection ofstreptozotocin.2) The diabetic heart may be more susceptible to I/R injuryin ourexperiment.3) Atorvastatin calcium postconditioning can still attenuate diabetic heartischemia-reperfusion injury, and the protective effect of2mg/kg atorvastatin calciumgroup was better than that of1mg/kg atorvastatin calcium group.4) The phosphorylation of GSK3β mediated atorvastatin calcium postconditioning reducemyocardial ischemia-reperfusion injury in streptozotocin induced diabetic rats.5)p-GSK3β can acceleration HSP70production partially by activating HSF-1duringMIRI.