Research On The IRE1-JNK Signaling Pathway Of Endoplasmic Reticulum Stress Mediated Motor Preconditioning Myocardial Protection

Research purpose: As a means of stimulation,the myocardial protection effect of exercise preconditioning has attracted much attention.Endoplasmic reticulum stress is an essential degradation pathway for myocardial health.Therefore,the protective effect of exercise preconditioning may be related to endoplasmic reticulum stress.Recent studies have shown that the IRE1-JNK pathway plays an important role in er stress.In this study,the effect of exercise preconditioning on IRE1-JNK signaling pathway in er stress was studied to explore the role and mechanism of IRE1-JNK signaling pathway in the myocardial protection of exercise preconditioning,and to verify the myocardial protection effect of exercise preconditioning,so as to further improve the theoretical system of the effect of exercise preconditioning on myocardial protection.Methods: Forty SPF C57BL/6J male mice purchased from Hunan Slaike Jingda Experimental Animal Co.,LTD were randomly divided into 4 groups: quiet Sham operation group（Sham）,quiet ischemia-reperfusion group（QI）,sports ischemia-reperfusion group（ES）and sports ischemia-reperfusion group（EI）,with 10 mice in each group.The exercise regimen established by Kemi et al was modified appropriately,and the mice were subjected to 8 weeks of long duration moderate intensity aerobic exercise treadmill training,running 6 days a week and resting 1 day,and the myocardial ischemia-reperfusion injury model was established.The morphological and structural changes of myocardial cells were observed by HE staining and TTC staining.The degree of myocardial injury was observed by detecting c Tn-I in serum of mice.Ers-related gene expression was detected by fluorescence quantitative PCR.The expression of IRE1-JNK signaling pathway related proteins and phosphorylation levels of factors in ERS were detected by Western blot.Results:1.Ecg results show that: Sham group before and after the operation,and has no obvious change,in mice before the left anterior descending coronary artery ligation of ST segment and has no obvious change,30 min of ischemia ecg ST segment appeared during back bow service,ST segment than normal period and after ischemia reperfusion period fell,cardiac myocardial ischemia-reperfusion injury in mice model set up successfully.2.HE staining results showed that after HE staining,myocardial cells of mice in Sham group and ES group were orderly and regular,with uniform staining,clear cell outline,oval nucleus,light blue staining,light red cytoplasm,and no swelling or increased eosinophilic phenomenon.A large number of cardiomyocytes in I/R group showed swelling and eosinophilic enhancement.A small number of myocardial cells in EI group showed swelling and eosinophilic enhancement,which was significantly less than that in I/R group.3.TTC staining results showed that the myocardium of mice in Sham group and ES group was red,without myocardial infarction area.Compared with Sham group,the myocardium of mice in I/R group showed obvious white area（P<0.05）;Compared with I/R group,the white area of myocardium in EI group decreased（P<0.01）.4.The myocardial troponin concentration of mice was measured by ELISA.The results showed that compared with Sham group,the myocardial CTN-I concentration of mice in I/R group was significantly increased（P<0.01）;Compared with ES group,the myocardial c Tn-I concentration in EI group was significantly increased（P<0.01）.Compared with I/R group,the myocardial c Tn-I concentration in EI group was significantly decreased（P<0.01）.5.The m RNA expression levels of GRP78,IRE1,TRAF2,ASK1 and JNK in I/R group were increased compared with that in Sham group（P < 0.05）.Compared with ES group,the m RNA expression levels of GRP78,IRE1 and TRAF2 in EI group were increased（P < 0.05）,while the m RNA expression levels of ASK1 and JNK were not significantly different（P > 0.05）.Compared with I/R group,the m RNA expression levels of GRP78,TRAF2,ASK1 and JNK in EI group were decreased（P < 0.05）,and the m RNA expression levels of IRE1 were not significantly different（P > 0.05）.6.The expression of er stress-related proteins detected by western blot showed that:Compared with Sham group,the protein expression levels of Caspase3,Bax,GRP78,IRE1,P-IRE1,TRAF2,ASK1,JNK,and P-JNK in I/R group were increased（P<0.05）,while the protein expression levels of Bcl-2 were decreased（P<0.01）.Compared with ES group,the protein expression levels of Caspase3,Bax,GRP78,IRE1,P-IRE1,TRAF2,ASK1,JNK,and P-JNK in EI group were increased（P<0.05）,while the protein expression levels of Bcl-2 were decreased（P<0.01）.Compared with I/R group,the protein expression levels of Caspase3,Bax,GRP78,IRE1,P-IRE1,TRAF2,ASK1,JNK,p-JNK in EI group were decreased（P<0.05）,while the protein expression levels of Bcl-2 were increased（P<0.01）.Conclusion : Long time moderate intensity aerobic exercise training can reduce myocardial ischemia reperfusion injury.Endoplasmic reticulum stress IRE1-JNK signaling pathway may be involved in the myocardial protection of exercise preconditioning.The protective effect may be caused by endoplasmic reticulum stress induced by exercise,which leads to apoptosis and activation of IRE1-JNK signaling pathway.