PPARαactivation inhibits astrocyte over acti⁃vation by restoring autophagy flux after tran⁃sient brain ischemia

OBJECTIVE Astrocytes activa⁃tion and glial scar formation are the important causes that hinder the recovery of motor function after cerebral ischemia.However,its precise mechanism has not been clarified.Peroxisome proliferator-activated receptorα(PPARα)is a ligand-activated nuclear transcriptional factor.This study aims to further clarify the role of PPARαin astrocyte activation after cerebral isch⁃emia and explore the underlying mechanism.METHODS Astrocyte activation in vivo model was induced by transient middle cerebral artery occlusion(tMCAO)in mice and in vitro model was induced by oxygen-glucose deprivation/reox⁃ygenation(OGD/R)in primary culture of mouse astrocyte.The effects of PPARαon astrocyte ac⁃tivation and autophagy flux were observed in the condition of PPARαdysfunction(PPARαnull mice)or PPARαactivation by oleoylethanol⁃amide(OEA).RESULTS PPARαmainly ex⁃pressed in activated astrocytes during the chron⁃ic phase of brain ischemia and PPARαdysfunc⁃tion promoted astrocytes activation after brain ischemia in vivo and in vitro.After cerebral isch⁃emia,the expressions of LC3-Ⅱ/Ⅰand P62 both increased in the brain tissue near the infarct core.Autophagic vesicles accumulation was ob⁃served by electron microscopy in astrocytes,and mRFP-GFP-LC3 adenovirus infection assay indi⁃cated the block of autophagy flux.PPARαdys⁃function aggravated autophagy flux block,while PPARαactivation preserved the lysosome func⁃tion and restored autophagy flux in astrocytes after OGD/R.Autophagy flux blocker bafilomycin A1 and chloroquine antagonized the effect of OEA on inhibiting astrocyte activation.CONCLU⁃SION PPARαactivation inhibites the over-activa⁃tion of astrocytes by restoring the autophagy flux after cerebral ischemia.