Therapeutic Effect Of Icariside Ⅱ On Neuroinflammation After Cerebral Ischemia-Reperfusion Injury By Mediating PPARα/γ Signaling Pathwy

Objective: To investigate the inhibitory effect and mechnism of icariside Ⅱ(ICS Ⅱ)on neuroinflammation after cerebral ischemia-reperfusion injury.Methods: Focal CIRI model was established by middle cerebral artery embolization in mice.Cerebral blood flow(CBF)of mice before and after modeling was measured by real-time imaging system.Male C57BL/6 mice were randomly divided into seven groups:sham operation group(sham),sham + ICS Ⅱ-high dose group(sham + ICS Ⅱ 24 mg/kg),model group(model),model + ICS Ⅱ-low,-medium and-high dose groups(model + ICS Ⅱ 6 mg/kg,ICS Ⅱ 12 mg/kg,ICS Ⅱ 24 mg/kg).ICS Ⅱ was given therapeutic administration of 6 mg/kg,12 mg/kg and 24 mg/kg for 3 days(twice a day)after CIRI,and the sham operation group and model group were intragastric with volume-matched normal saline.After three days,the changes of neurological function were observed by modified Longa5-point method.The changes of cerebral infarction volume were observed by TTC staining.The motor sensory function of mice was observed using rotating rod test and adhesion removal test.The learning and memory function was observed by Y maze experiment.The levels of pro-inflammatory factors IL-1 β,IL-6,TNF-α,i NOS and anti-inflammatory factors IL-4 and IL-10 in cerebral ischemic penumbra(CIP)were determined by ELISA.Immunohistochemical staining was used to detect the expression of astrocytes and microglia in the cortex of mice.The expression of inflammatory pathway-related proteins in mouse brain was detected by Western blot method.Results: Compared with the sham group,mice of model group showed significantly neurological function deficits,while,ICS Ⅱ markedly increased the neurological function in a dose-dependent manner than those of model group.Moreover,the size of cerebral infarction of mice in the model group was significantly increased compared with that in the sham group,while,ICS Ⅱ significantly decreased the size of cerebral infarction compared with that in the model group.Of note,ICS Ⅱ also improved the motor sensory function and the learning and memory function than those of model group.Furthermore,the levels of TNF-α,IL-1 β,IL-6 and i NOS in the brain tissue of model group were significantly increased,the levels of IL-4 and IL-10 were decreased;while,ICS Ⅱ significantly reversed these change.ICS Ⅱ also inhibited the activation of astrocytes and microglia than those of model group.What is more,ICS Ⅱ significantly increased the protein expression of peroxisome proliferator activated receptor(PPAR α)and PPAR γ than those of model group,but did not affect the protein expression of PPARβ.In addition,ICS Ⅱ significantly down-regulated the phosphorylation levels of NF-κBp65,NF-κBp50,IKKβ and IKKαup-regulated the protein expression of IκB than those of model group.Conclusion: ICS Ⅱ exerts anti-neuroinflammatory effects after CIRI in mice,through mediation of PPARα/γ signaling pathway,thereby promoting the anti-inflamamtory cytokines release and mitigating the pro-inflammatory cytokines level.