| Purpose:To analyse the correlation between two evaluation methods of middle cerebral artery occlusion and focal cerebral ischemia,and to explore a new method and standard for the evaluation of the model.To investigate the protective effect of Hyp against focal cerebral ischemia-reperfusion in rats and the role of BK channel in this effect.To explore the mechanism of Hyp on brain ischemia injury.Methods:1.Twenty adult male kunming mice were randomly divided into a model group and a sham-operated group.The focal cerebral ischemia reperfusion model was established by thread embolism method,and the changes of cerebral blood flow in each group were detected before,immediately,2 hours after the ischemia,immediately and 24 hours after reperfusion,the rating systerm was employed to evaluate neurological function of mice at 24 h after ischemia reperfusion,the brain infract volume percentage was assesed after 2% TTC staining following the last neurological evaluation,and the correlation between the infarct volume and cerebral blood flow ratio was analyzed by correlation analysis.2.Local cerebral ischemia-reperfusion model in rats were established by an intraluminal filament.Healthy male SD rats were randomly divided into 6 groups:sham group?model group?I/R rats treated with Hyp at 12.5,25,50mg/kg doses and GBE at a dose of 60mg/kg.the changes of cerebral blood flow in each group were detected before?immediately?2 hours after ischemia?immediately and 24 hours after reperfusion by using lSI.After 24 hours of reperfusion,the neurological deficit scores were evaluated and the brain infact volume percenage was assesed after TTC staining.3.Serum levels of MDA and SOD contents were evaluated.4.Expression levels of BK-??BK-?4 ?PKC-? mRNA in neurons were detected by RT-PCR.5.BK-??BK-?4?PKC-? in neurons and BK-b1 in vascular were measured via western blot.Results:1.Compared with sham group,the mice in the model group had obvious neurological abnormalities,the TTC staining showed obvious infarction,and the cerebral blood flow of the infarct side was significantly decreased(P<0.05).The correlation coefficient of the cerebral blood flow and the infarct volume at 24 h after reperfusion were 0.55 and 0.28(P<0.05),respectively.2.Compared with sham group,the rats in the model group significantly increased neurological abnormalities and infarct volume(P<0.01);Compared with model group,Hyp(12.5,25,50mg/kg)significantly ameliorated neurological deficit score and infarct volume(P<0.05,P<0.01).The cortical blood flow in model and Hyp treatment group were significantly reduced compared with sham group(P<0.05),treatment with medium and high Hyp could significantly increased cerebral blood flow 24 hours after reperfusion(P<0.01).3.The contents of MDA was significantly increased and the contents of SOD was decreased obviously compared with sham group(P<0.01).Application of Hyp(12.5,25,50mg/kg)could significantly inhibited the decrease of SOD and the increase of MDA(P<0.05,P<0.01).4.The expression of BK-??PKC-? mRNA in neurons were reduced and BK-?4 mRNA was increased compared with sham group(P<0.01).Hyp(12.5,25,50mg/kg)could up-regulated the expression of BK-??PKC-? mRNA.Meanwhlie,BK-?4 mRNA was significantly down-regulated.5.Compared with model group,medium and high Hyp groups significantly increased the BK-??PKC-? protein levels in neurons(P<0.01),also,significantly reduced BK-?4 protein level in neurons.In vascular smooth muscle,Hyp(25,50mg/kg)could increased BK-?1 protein level(P<0.05,P<0.01).Conclusion:1.There was a high linear correlation between cerebral infarct volume at 24 h reperfusion and cerebral blood flow immediately after ischemia in model group.Bseides using the neurological function evaluation and infarct volume,monitoring of cerebral blood flow is a reliable and useful method to confirm the successful establishment of mouse MCAO model.2.Hyp treatment effectively ameliorated the neurological defect,infarct volume by means of enhancement of antioxidant and increase cerebral blood flow which is contribruted to the activation of BK channels and PKC in neurons and vacular smooth muscle cells. |
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