The Protective Effect And The Relative Mechanism Of Swertiamain On Cerebral Ischemia Injury

Object This study is to explore whether Swe could prevent brain from ischemia injury and the related mechanisms of oxidative stress is also elucidated using middle cerebral artery occlusion（MCAO）model and primary hippocampal neurons oxygen-glucose deprivation/reperfusion（OGD/R）model.Methods 1.Swe（25,100,or 400 mg/kg）was pre-treated intraperitoneally for 7 days until establishment of the MCAO model.TTC staing and neurologic scores was performed to detect infarct volume and neurologic recovery.Rotating rod and gripping force experiment were performed to observe autonomous coordination motor function.HE staining and TUNEL staining was performed to examine the damage of the brain tissue.Oxidative damage was assessed by measuring the production of SOD,GSH-PX,CAT,GSH and MDA contents.2.Hippocampal neurons were subjected to OGD/R and maintained in Swe（0.1,1 or 10μM）in the entire process of reoxygenation.Cell viability,LDH release,intracellular Ca²⁺and MMP were detected to explore the protective effect of Swe on hippocampal neurons.Moreover,the release of Nrf2 from Keap1-Nrf2 complex,the nuclear distribution of Nrf2,the protein expression of Nrf2,HO-1,NQO1 and the mRNA level of HO-1,NQO1 were measured to confirm the function of Nrf2 pathway in Swe induced neuroprotection.Results The infarct volume in vehicle group was remarkably higher than that in the sham group（p<0.01）.Pre-treatment of Swe dose-dependently reduced infarct volume.The neurological deficit score of the vehicle group were significantly increased（p<0.01）compared with the sham group.In the pre-treated groups with Swe（100 and 400 mg/kg）,the neurological deficits were significantly decreased（p<0.01）.Compared with vehicle group,Swe significantly increased the grip strength and the time of movement on the rotating rod in mice.Swe pre-treatment markedly decreased the cell apoptosis（p<0.01）,oxidative damage（p<0.05,p<0.01）and reversed the change of pathological to a certain extent.Swe also decreased reactive oxygen species（ROS）,LDH release and increased cell viability in vitro（p<0.05,p<0.01）.Compared with OGD/R group,Swe maintained MMP and decreased the concentration of intracellular Ca²⁺（p<0.05,p<0.01）.Western blot analyses and immunofluorescence staining demonstrated that Swe pre-treatment promoted Nrf2 nuclear translocation from Keap1-Nrf2 complex and enhanced the expressions of NQO1and HO-1,while the expressions could be reversed by a Nrf2 inhibitor.Conclusion We found the preventive potential of Swe for ischemic brain damage.This protection potentially relied on antioxidative stress capabilities that were mediated by activating the Nrf2 protective pathway.