Atg7 Knockout Effect Promoted The Cerebral Protective Effect Of Ischemic Postconditioning By Reducing Autophagy

Objective:Ischemic postconditioning can reduce cerebral ischemia-reperfusion injury by activating autophagy during early reperfusion.Autophagy completes the process of autophagy through a series of autophagy related proteins,among which Atg7 is an essential protein for autophagy binding system and autophagosome formation,which plays an important regulatory role in autophagosome formation.The aim of this study was to investigate the role of Atg7 in the protection of brain tissue after cerebral ischemic postconditioning.Methods:Rats with Atg7 knockout and SD rats were used.Middle cerebral artery infarction(MCAO)model was established by thread occlusion method,and cerebral ischemia-reperfusion and ischemic postconditioning were performed respectively.The severity of neurological deficit after cerebral infarction was evaluated by modified MNSs score.The area of cerebral infarction was measured by TTC staining.The brain edema was measured by dry wet weight method.The protein expression levels of LC3-Ⅱ and Beclinl in ischemic penumbra were detected by Western blot.The expression of Atg7 in ischemic penumbra was detected by immunohistochemistry.Results:1.mNSS score showed that the score of sham group was 0,except for sham group,the scores of other groups were increased,and the scores of the I/R group were significantly increased,and the neurological function loss was the most serious;IPostC group was lower than I/R group(P<0.05,the difference was statistically significant);Compared with the IPostC group,the score of the Atg7-/-IPostC group was significantly lower(P<0.05,the difference was statistically significant).Compared with Atg7-/-IPostC group,the score of Rapa+Atg7-/-IPostC group was increased(P<0.05,the difference was statistically significant).2.TTC staining results showed that compared with sham group,the other four groups had different degrees of infarction.The volume of cerebral infarction in I/R group was the largest,and that in IPostC group was lower than that in I/R group(P<0.05,the difference was statistically significant).Compared with the IPostC group,the size of cerebral infarction was significantly reduced in the Atg7-/-IPostC group,and only a small infarct area could be observed at the edge(P<0.05,the difference was statistically significant).Compared with the Atg7-/-IPostC group,the infarct volume in Rapa+Atg7-/-IPostC group was increased(P<0.05,the difference was statistically significant).3.The results of brain water content showed that the brain water content in I/R group was the highest,indicating obvious brain edema.IPostC group was lower than I/R group(P<0.05,the difference was statistically significant);Compared with IPostC group,brain water content in Atg7-/-IPostC group decreased(P<0.05,the difference was statistically significant).Rapa+Atg7-/-IPostC group was higher than Atg7-/-IPostC group(P<0.05,the difference was statistically significant).4.Western Blot analysis showed that the expression levels of LC3-Ⅱ and Beclinl in I/R group were higher than those in IPostC group(P<0.05,the difference was statistically significant).Compared with IPostC group,Atg7-/-IPostC group was significantly decreased(P<0.05,the difference was statistically significant).Compared with the Atg7-/-IPostC group,the RAPA+Atg7-/-IPostC group increased(P<0.05,the difference was statistically significant).5.Immunohistochemical test results showed that the expression of Atg7 in Ipostc group was decreased compared with that in I/R group(P<0.05,the difference was statistically significant).Compared with the IPostC group,the Atg7-/-IPostC group was significantly decreased(P<0.01,the difference was statistically significant).Compared with the Atg7-/-IPostC group,the expression of Atg7 was increased in Rapa+Atg7-/-IPostC group(P<0.05,the difference was statistically significant).Conclusion(s):1.Ischemic postconditioning can reduce the damage caused by cerebral ischemia-reperfusion.2.Atg7 knockout attenuates autophagy after cerebral ischemia.3.Atg7 knockout enhances the neuroprotective effect of postconditioning on ischemia-reperfusion induced acute brain injury.