| Ischemic stroke is a kind of brain disease with devastating neurological impairment,which has become a major public health event due to its high mortality and disability rate.Restoring blood supply is a relatively effective method.However,a series of ischemia reperfusion injury will occur with the recovery of blood supply to brain tissue.At present,it has been found that autophagy and apoptosis of nerve cells are closely related to cerebral ischemia reperfusion injury,but the exact molecular biological mechanism is not fully understood.The mammalian target of rapamycin(mTOR)is an important signal transduction molecule,which plays an important role in ischemic stroke by regulating autophagy and apoptosis.Rheb is a necessary stimulator protein of mTOR activation,which is involved in the regulation of mTOR signaling pathway.Recent studies have found that miR-155 plays a role in the cellular oxygen glucose deprivation model by inhibiting the Rheb/mTOR signaling pathway.However,whether miR-155 and Rheb/mTOR signaling pathway involved in animal cerebral ischemia reperfusion injury and its specific mechanism has been rarely studied.Therefore,this study aims to explore the mechanism of miR-155 and the Rheb/mTOR signaling pathway in the model of cerebral ischemia-reperfusion injury in rats,and provide theoretical basis for further exploring the therapeutic targets for neuroprotection after cerebral ischemia-reperfusion injury.Methods: In this study,the rats were randomly divided into 5 groups,the Sham group,the MCAO/R group,the MCAO/R+LV-miR-155 group,the MCAO/R+LV-miR-155 Sponge group and the MCAO/R+LV-miR-155 Scrambled group.The expression of miR-155 was regulated by stereotactic intracerebral injection of recombinant lentivirus.The middle cerebral artery occlusion reperfusion(MCAO/R)model of rats was established 7 days later.The neurological deficit score was evaluated 4hours after reperfusion,and the score was 2-3 points.Brain tissues in the ischemic penumbra were taken after 24 h reperfusion.The q RT-PCR and Western blotting were used to detect the m RNA and protein levels of Rheb and mTOR,S6k1 and 4Ebp1 in mTOR signaling pathway when different miR-155 expression levels.Result:(1)In MCAO/R model of rat,neurological deficit score and TTC staining were performed to confirm the successful establishment of cerebral ischemia reperfusion model.(2)In the ischemic penumbra of rats 24 h after cerebral ischemia reperfusion,the expression level of miR-155 was significantly decreased in the MCAO/R group compared with the Sham group(P<0.05).Compared with the MCAO/R group,the expression level of miR-155 was increased in the MCAO/R+LV-miR-155 group and decreased in the MCAO/R+LV-miR-155 Sponge group(P<0.05).(3)In the ischemic penumbra of rats 24 h after cerebral ischemia reperfusion,the m RNA expression levels of Rheb,mTOR,4Ebp1 and S6k1 were decreased in the up-regulated miR-155 group and increased in the down-regulated miR-155 group compared with the MCAO/R group(P<0.05).(4)In the ischemic penumbra of rats 24 h after cerebral ischemia reperfusion,the protein expression levels of Rheb,mTOR,4Ebp1 and S6k1 were decreased in the up-regulated miR-155 group and increased in the down-regulated miR-155 group compared with the MCAO/R group(P<0.05).(5)In the ischemic penumbra of rats 24 h after cerebral ischemia reperfusion,the phosphorylation protein expression levels of mTOR,4Ebp1 and S6k1 levels were decreased in the up-regulated miR-155 group and increased in the down-regulated miR-155 group compared with the MCAO/R group(P<0.05).Conclusion:(1)In the rat MCAO/R model,miR-155,Rheb and mTOR signaling pathway are involved in the cerebral ischemia reperfusion injury in the ischemic penumbra.(2)In the rat MCAO/R model,miR-155 may be involved in the occurrence of cerebral ischemia reperfusion injury in the ischemic penumbra by inhibiting the m RNA and protein expression levels of Rheb and mTOR signaling pathway.(3)In the rat MCAO/R model,miR-155 may be involved in the occurrence of cerebral ischemia reperfusion injury in the ischemic penumbra by inhibiting the protein phosphorylation levels of mTOR signaling pathway. |
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