Effect Of TGF-beta 1/ERK5 Signaling Pathway On Isoflurane Postconditioning Against Rat Hippocampal Oxygen And Glucose Deprivation

Object:To evaluate the protective effect of isoflurane postconditioning against oxygen-glucose deprivation injury and investigated the role of TGF-β1 and ERK5 in this neuroprotective mechanism.And to provide new insights into the molecular mechanisms underlying anti ischemic brain injury for isoflurane.Methods: Male Sprague-Dawley rats(weight range of 50~100g)were anesthetized and then isolated the hippocampus to preparation into slices.And then they were randomly divided into the treatment of normal control group(CON group),injury group(OGD group),different concentrations of isoflurane postprocessing(1.5%ISPOC,3.0%ISPOC and 4.5%PSPOC group),DMSO group,inhibitors(LY group and XMD group)and 3.0%ISPOC+inhibitors(3.0%ISPOC+LYgroup and 3.0%ISPOC+XMD group).The extent of each group of hippocampal slices with OGD injury was tested by 2%2,3,5-triphenyltetrazolium chloride(TTC)staining.To detect the neuronal necrocytosis of each group of hippocampus CA1 region,propidium iodide(PI)fluorescence was adopted.Expression level of TGF-β1 were determined by immunostaining.The expression of Smad2,Smad3 and ERK5 m RNA was determined by real-time fluorescence quantitative PCR.The expression of TGF-β1,Smad2/3 and ERK5 protein and the level of phosphorylation was detected by Western blot.Results:Compared with group 1.5%ISPOC and 4.5%ISPOC,the degree of slices injury and necrocytosis of hippocampal CA1 neurons were significantly decreased,and expression of TGF-β1,p-Smad2/3 and p-ERK5 were significantly up-regulated in group 3.0%ISPOC(P<0.05).After inducing the TGF-β1 blocker(LY2157299)or the ERK5 blocker(XMD8-92),the degree of slices injury and necrocytosis of hippocampal CA1 neurons were significantly increased,compared with group 3.0%ISPOC(P<0.05).Immunofluorescence results showed that,the expression of TGF-β1 could be seen in the cytoplasm of 3.0%ISPOC group CA1,but no obvious expression was observed after the LY2157299 and XMD8-92(P<0.05).In addition,the expression levels of Smad2,Smad3 and ERK5 m RNA were significantly decreased after inducing the LY2157299 and XMD8-92(P<0.05).Compared with group 3.0%ISPOC,to block the corresponding signal protein expression decreased obviously after agent.And after inducing the LY2157299,the expression level of p-Smad2/3 and p-ERK5 decreased;after inducing the XMD8-92,the expression level of TGF-β1 and p-Smad2/3 expression was also decreased(P<0.05).Conclusions:Acertain concentration of isoflurane postprocessing has a neuroprotective effect on rat hippocampal OGD injury.The neuroprotective mechanism of TGF-β1 and ERK5 signaling pathways involved in isoflurane postprocessing,and mutual interaction coordination.