Effects Of Exercise Preconditioning Of Exosome Mediated MiR-124 On Apoptosis In Cerebral Ischemia-Reperfusion Rats

Objective:To investigate the effects of exercise preconditioning on plasma exosome miR-124 content and early apoptosis via exosome miR-124,STAT3,BCL-2 and BAX pathways in rats with cerebral ischemia-reperfusion injury,and to provide a theoretical basis as well as a scientific basis for exercise preconditioning as a preventive and curative measure for ischemic stroke.Methods:The 180 rats were divided into 4 groups by random number table method,namely,exercise preconditioning+sham group(P-Sham),sham group(Sham),exercise preconditioning+model group(P-Model)and model group(Model).Among them,the P-Sham group and the P-Model group were trained with running wheels for 30min every day,six days a week for 4 weeks,and the model was established for each group of rats after 24h of the last exercise preconditioning.After 6h,12h and 24h of reperfusion,mNSS was used to evaluate the neurological impairment;TUNEL staining was used to observe apoptosis in the ischemic side of the rat brain;TTC staining was used to determine the area of cerebral infarction;transmission electron microscopy and nano-flow detector were used to identify plasma exosomes,and Real-Time PCR was used to detect the expression of miR-124 in plasma exosomes;Western blot was used to detect the expression of STAT3,BCL-2 and BAX in ischemic brain tissue.and immunohistochemistry was used to detect the positive expression of BCL-2 and BAX in ischemic brain tissue,and to observe the changes of miR-124,STAT3,BCL-2 and BAX expression in cerebral ischemia/reperfusion rats after exercise preconditioning.To elucidate that exercise preconditioning inhibits apoptosis caused by cerebral ischemiareperfusion injury through exosome-mediated miR-124,STAT3,BCL-2,and BAX pathways.Results:1.The results of the mNSS scores showed that the rats in the P-Sham group and the Sham group did not show a significant increase in the scores after modeling,while the scores in the other two groups showed different degrees of increase(P<0.05).The scores of rats in the P-Model group were lower than those in the Model group at 6h,12h and 24h(P<0.05).2.TTC staining showed that 1d after cerebral ischemia-reperfusion injury in rats,no infarct foci were seen in the P-Sham and Sham groups,but obvious infarct foci appeared in the P-Model and Modle groups,and the infarct area of rats in the P-Model group was much smaller than that of rats in the Modle group(P<0.01).3.TUNEL staining showed that after 6h,12h and 24h of cerebral ischemiareperfusion,there were only a very small number of apoptotic cells in the PSham and Sham groups,while a large number of apoptotic cells were seen in the P-Model and Model groups,and the number of apoptotic cells in the PModel group was less than that in the Model group(P<0.01).4.The results of plasma exosome miR-124 expression showed that the exosome miR-124 levels were higher in the P-Model group than in the Model group at the 6h and 24h time points after cerebral ischemia-reperfusion(P<0.05),and the exosome miR-124 levels were much higher in the P-Sham group than in the Sham group at all three time points(P<0.01).5.The results of STAT3 expression in brain tissues showed that after 6h,12h and 24h of cerebral ischemia-reperfusion in all groups,the expression of STAT3 in brain tissues of rats in the P-Model group was lower than that in the Model group at the time point of 24h(P<0.01),and the expression of STAT3 in brain tissues of rats in the P-Sham group was lower than that in the Sham group at the time point of 24h(P<0.05).STAT3 expression was lower in the P-Model and P-Sham groups at 12h and 24h than at 6h(P<0.05),Model group showed lower expression at 12h than at 6h and 24h(P<0.05).6.The results of BCL-2 expression in brain tissues showed that after 6h,12h and 24h of cerebral ischemia-reperfusion in all groups of rats,BCL-2 expression in brain tissues of P-Model group was higher than that of Model group at 6h and 24h(P<0.05),and BCL-2 expression in brain tissues of PSham group was higher than that of Sham group at 12h and 24h(P<0.05).BCL-2 expression in the P-Model and P-Sham groups was higher at 12h and 24h than at 6h(P<0.05),and BCL-2 expression in the Model group was higher at 12h than at 6h and 24h(P<0.05).7.The results of BAX expression in brain tissues showed that after 6h,12h and 24h of cerebral ischemia-reperfusion in all groups of rats,a large amount of BAX expression was seen in brain tissues of P-Model group and Model group,which was significantly more than that of P-Sham group and Sham group(P<0.01),and the expression of BAX in brain tissues of P-Model group at the time point of 24h was significantly lower than that of Model group(P<0.01).The expression of BAX in the brain tissue of P-Model group was significantly lower than that of Model group(P<0.01),and the expression of BAX in Model group at 24h was higher than that of 6h and 12h(P<0.05).Conclusions:1.Exercise preconditioning reduced apoptosis,decreased infarct size and exerted neuroprotective effects after cerebral ischemia/reperfusion injury.2.Exercise preconditioning inhibits apoptosis through exosomal miR-124,STAT3,BCL-2 and BAX pathways in rats with cerebral ischemia/reperfusion injury.