The Study On Inflammatory Reaction And Its Protective Mechanism After Cerebral Ischemia-reperfusion

Objective To observe the changes of neuronal activity,structure and function induced by inflammation after cerebral ischemia-reperfusion,and investigate the protective mechanisms of microglia polarization on early cerebral ischemia-reperfusion injury.Methods 72 healthy male C57bl/6 mice were randomly divided into sham-operation group,ischemia-reperfusion 24h group and ischemia-reperfusion 72h group.The Middle Cerebral Artery Occlusion(MCAO)was used to establish the model of Cerebral ischemia-reperfusion injury in mice.In each group,6 mice use TTC stain to observe the change of infarct volume,6 mice use immunofluorescence stain to judge the change of nerve cell activity,6 mice use Western blotting to detect the expression of Caspase-3,GFAP,i NOS on the M1 Microglia,Arg-1 on M2 Microglia,6 mice use q PCR to observe the expression of inflammatory factors for i NOS,TNF-α,the expression of anti-inflammatory factors for Arg-1,TGF-β,and CD16/32,CD206 on the M1 and M2 Microglia.Results There were obvious infarct volume,decreased activity of nerve cells,apoptosis of nerve cells and damage of nerve function in ischemia-reperfusion group 24h and 72h.Compared with the mice in ischemia-reperfusion group 24h,after 72h of ischemia-reperfusion,the activity of neurons in mice was restored.In the early stage of ischemia-reperfusion,the astrocyte are activated and the cell bodies become hypertrophic.At 24h after ischemia-reperfusion injury,the expression of CD16/32,a marker molecule of inflammatory factor,i NOS,TNF-α and M1 Microglia,was significantly increased.At 72h after ischemia-reperfusion injury,the expression of CD206,a marker molecule of anti-inflammatory factors,Arg-1,TGF-β,and M2 Microglia,was increased.Conclusions The model of MCAO was established successfully in mice.The astrocyte was activated by ischemia-reperfusion injury.In the early 24h after ischemia-reperfusion,the activated Microglia exhibited M1 pro-inflammatory phenotype,releasing inflammatory factors,aggravating tissue injury and neuronal apoptosis,and the inflammatory response was obvious.At 72h after ischemia-reperfusion,microglia transformed to M2 anti-inflammatory phenotype,releasing neuroprotective factors and repairing tissue damage.Different polarization levels of Microglia play an important role in the regulation of inflammatory response and neuroprotection after cerebral ischemia-reperfusion injury,and may become a new target for clinical treatment of ischemic stroke.