The Protective Effects of Ischemic Postconditioning on Ischemic Peperfusion of Pancreas Transplantation and Its Mechanisms in Homogeneity Rats
|School||Central South University|
|Keywords||Ischemic postconditioning pancreas transplantation ischemia-reperfusion apoptosis|
Ischemic-reperfusion injury is one of main cause that is result in various kinds complication after pancreas transplanations,as earlier pancreatitis、primarily nonfunction of graft、islet cell cacergasia,these complication largely lower the effect of pancreas transplanations. Discovered by study,preconditioning can diminish the injury of ischemic reperfusion effectively,so it have the protective effect to transplanted organ.But it is confined in clinical application.Postconditioning have the same protection as preconditioning,and the intervention method is convenient.whether or no postconditioning have the protection after pancreas transplantion,at present no literature be reported.The objective of the study is to establish a physiologic Pancreas transplantation model in diabetes rats,to investigate the protection and postconditioning plan of ischemic postconditioning,to investigate the antioxidative and against the apoptosis mechanism of ischemic postconditioning.PartⅠEstablishment of Pancreas Transplantation Model in diabetes Rats Objective:To establish a physiologic Pancreas transplantation model in homogeneity diabetes rats for the further study.Methods:36 diabetes rats as the transplant recipients were induced by a single intravenous injection of streptozocin(STZ)at dose of 65mg/kg of body weight in the 50 SD rats.Another normal 36 SD rats were used as donor. Pancreaticoduodenal transplantation alone(PTA)was performed between normal rats and diabetic rats with portal venous drainage and enteric drainage.General state of health,the level of blood glucose,morphologic change and function of graft were observed after operation.Results:36 cases of PTA in rats was operated,30 rats was live more than 24 hours. the success rate of transplantation was 83.3%.After transplantation rats were in good condition.The lever of blood glucose was less than 11.2mmol/L,and that is in the descend tendency in a week.Histological characteristic of grafts were seen:glandular lobule outline was integrity,a few inflammatory cell infiltrate were in pancreatic island.Conclusion: This model of pancreas transplantation in diabetics rats is stable and reliable,and can be utilized for the further scientific study.Part 2 The protective effects of ischemic postconditioning on ischemic peperfusion of pancreas transplantation and its mechanisms in homogeneity ratsObjective:To investigate whether or no postconditioning have the protection after pancreas transplantion,the best postconditioning plan and the mechanism of protection.Methods:60 SD rats were randomly divided into 5 groups according with randomized block design to be operated(16 SD rats were sham operated group(Sham,n=16),44 diabetes rats were ischemic/reperfusion group(Control,n=16)and ischemic postconditioning group(IPO,n=28);IPO group diabetic rats was randomly divided 3 subset groups:IPO1(n=6),IPO2(n=16)and IPO3(n=6),After operation,the contents of malondialdchyde(MDA)and glutathione(GSH),the activity of superoxide dismute(SOD),myloperoxidase(MPO)and GSH-Px were determined respectively by spectrophotometer.The number of pancreas apoptotic cells were measured by the method of TUNEL staining. Pancreas tissue samples were taken not only for RT-PCR to detect Bcl-2 and Bax mRNA expression,but also for western blot and immumne-chemical analysis of detection Bcl-2 and Bax proteine expression.Result:Compared with before being operated,The blood glucose level in Control and IPO groups decreased obviously after being operated,and the IPO2 group’s blood glucose were lower than other groups(P＜0.05),Histological characteristic of grafts in IPO groups are better than Control group,and that in the IPO2 group is the best in the IPO groups. Compared with the Sham group,the contents of MDA and activity of MPO in Control group and IPO group were significantly increased, The contents of GSH and activity of SOD and GSH-Px were significantly reduced(P＜0.05),the apoptosis cells in the Control group and IPO group increased significantly(P＜0.05),the expression of mRNA and protein of Bcl-2 and Bax increased significantly(P＜0.05).Compared with the Control group,the contents of MDA and activity of MPO in IPO group were significantly reduced,the contents of GSH and activity of SOD and GSH-Px were significantly increased.(P＜0.05), the apostosis cells is obviously less(P＜0.05),the expression of mRNA and protein of Bcl-2 increased significantly(P＜0.05),while the expression of mRNA and protein of Bax decreased significantly(P＜0.05).Conclusion:1.Ischemic postconditioning can protect graft from ischemic reperfusion injury after pancreas transplantation.2.Received PTA and then exposed ischemic postconditioning with 30s ischemic and 30s reperfusion three times before fully reperfusion is the best way to induce ischemic postconditioning in rats’ pancreas transplantation.3.The protective effect of ischemic postconditioing against ischemia-reperfusion injury may be related to reducing the Production of reactive oxygen species,maintaining the activities of antioxidant systems and suppressing neutrophil exsudation.4.The protective effect of ischemic postconditioning against Ischemia-reperfusion injury may be correlated with upregulating Bcl-2 mRNA and protein expression and downregulating the Bax mRNA and protein expression.