Effects Of Sevoflurane Postconditioning On Brain Injury And Autophagy In Rats With Ischemia-reperfusion

Objective:To evaluate the effects of sevoflurane postconditioning on brain injury and autophagy in rats with ischemia-reperfusion.Methods:1.Experiment objects and grouping:Seventy-five clean healthy male Sprague-Dawley rats(280~350 g)were randomly divided into five groups : sham operation group(S group),cerebral ischemia-reperfusion group(I/R group)and0.5MAC,1MAC,1.5MAC sevoflurane postconditioning groups(SPI,SPII,SPIII groups).2.Preparation of cerebral ischemia reperfusion injury and sevoflurane postconditioning model:Middle cerebral artery occlusion models were established by Zea-Longa middle cerebral artery occlusion,ischemia for 2h followed by reperfusion,and SP groups were subjected to differently concentration sevoflurane for 30 min in the begining of reperfusion.3.Neurological deficit score and determination of cerebral infarction volume: Rats from each group and performed neurological function scores(NDS)at 24 h by reperfusion.After 72 h,they were sacrificed to determine the infarct volume ratio by TTC method.4.Western blot determination of autophagy markers:Rats were sacrificed at 2h by reperfusion.The cerebral cortex was taken and Western blot was used to detect thechanges of LC3-Ⅱ/LC3-Ⅰand beclin-1.5.Observation of number of autophagosomes by electron microscope: Rats were perfused with 4% para-formaldehyde through heart at 2 h by reperfusion.Taking fresh rat cerebral cortex used for making specimens,which was fixed in 5% glutaraldehyde and observe the number of autophagosomes under the transmission electron microscopy.Results:1.The scores of neurological deficit in rats showed : compared with S group,neurological deficit scores increased at 24 h in other groups(P<0.05);Compared with I/R group,neurological deficit scores in SP groups were decreased(P<0.05);Compared with the SPI group,the neurological scores in the SPII and III groups were reduced,and the SPIII group was greater than the SPII group(P<0.05).2.Infarct volume results showed:Compared with S group,the cerebral infarct volume was significantly increased in other groups(P<0.05);compared with I/R group,the cerebral infarct volume of SP groups was significantly decreased(P<0.05).Compared with the SPI group,the cerebral infarct volume was significantly reduced in the SPII and III groups,and the SPIII was smaller than the SPII(P<0.05).3.Western blot analysis showed:Compared with S group,the expressions of LC3-II/LC3-I and Beclin-1 were up-regulated in cerebral cortex of each group(P<0.05).Compared with the I/R group,the SP groups was down-regulated(P<0.05).Compared with SPI group,the expression of LC3-II/LC3-I and Beclin-1 in cerebral cortex of SPII and SPIII groups were down-regulated,and that of SPIII group was lower than that of SPII group(P<0.05).4.The results of transmission electron microscopy showed:Compared with S group,the number of autophagosomes in the cerebral cortex of the I/R,SPI,and SPII groups were increased(P<0.05),and the number of autophagosomes in SPIII groupincreased,but there was no statistical significance(P>0.05);Compared with the I/R group,the number of autophagosomes in the cerebral cortex of SP groups was decreased(P<0.05);compared with the SPI group,the expression of the number of autophagosomes in the cerebral cortex of the SPII and III groups was reduced,and the SPIII group was less In the SPII group(P<0.05).Conclusion:Post-treatment with sevoflurane can reduce focal cerebral ischemia-reperfusion injury in rats and there is a dose-dependent relationship,its mechanism may be related to inhibition of autophagy...