Effect Of Hypoxic Preconditioning On Learning And Memory And The Mechanism Research In Cerebral Ischemia-reperfusion Mice

Purpose:1．The effect study of hypoxic preconditioning on learning and memory in cerebralischemia-reperfusion mice.2．The effect study of hypoxic preconditioning on hippocampal CA1neuronalapoptosis in cerebral ischemia-reperfusion mice.3．The effect study of hypoxic preconditioning on hippocampal CA1expression ofMAP-2in cerebral ischemia-reperfusion mice.Methods：1.30healthy adult male Kunming mice, weighting from18-22g,were randomlydivided into five groups: Normal group(N group), hypoxic preconditioning group (HPCgroup),sham operation group (C group), ischemia-reperfusion group(O group), hypoxicpreconditioning and ischemia-reperfusion group(HPC+O group),with6mice in each group.Behavioral tests with Morris water maze. Recorded the average escape latency in placenavigation test, and recorded views across platforms and platform quadrant swimming timein the probe trial.2．132healthy adult male Kunming mice, weighting from18-22g,were randomlydivided into five groups: Normal group(N group), hypoxic preconditioning group (HPCgroup),sham operation group (C group), ischemia-reperfusion group(O group), hypoxicpreconditioning and ischemia-reperfusion group(HPC+O group),at the same time, the Ogroup and HPC+O group were randomly divided into ischemia-reperfusion1d、3d、7d and24d group,with12mice in each group；HPC+O group were given hypoxic preconditioningbefore24h of ischemia-reperfusion. O group and HPC+O group were removed the brainsat each hour respectively; C group were removed the brains at the24th after operation,HPC group were removed the brains at the24th after hypoxic preconditioning, N group were removed the brains immediately. Detection of brain tissue by immunofluorescencestaining. Observating the situation of hippocampal CA1neuronal apoptosis under afluorescence microscope；Observating the hippocampal CA1expression distributed anddynamic changes of microtubule-associated protein-2(MAP-2) under a fluorescencemicroscope.All experimental data were presented as mean±standard deviation(x s),statistical test was processed by SPSS13.0software package One Way ANOVA,significant level was P<0.05.Results:1．The experiment successfully copied the model of hypoxic preconditioning and themodel of ischemia-reperfusion group.2．The results the Morris water maze showed that: compared with N group, thelearning and memory ability in HPC group increased obviously, the difference wasstatistically significant, P<0.05; the learning and memory ability in HPC group decreaseobviously, P<0.05; compared with O group, the learning and memory ability in HPC+Ogroup increased obviously, the statistics showed significant difference, P<0.01.3． Detection the neuronal apoptosis by immunofluorescence staining under afluorescence microscope: After the success of ischemia-reperfusion model, the apoptosis ofnerve cells increased, particularly at the3th; compared with N group、C group、HPC group,the apoptosis of nerve cells in HPC+O3d group increased, the statistics showed significantdifference, P<0.05; there was no significant difference between HPC+O1d、7d、14d groupand N group、C group、HPC group, P>0.05.4．Detection the expression of MAP-2by immunofluorescence staining under afluorescence microscope: After the success of ischemia-reperfusion model, the positiveexpression rate of MAP-2increased, particularly at the7th; compared with O group, thepositive expression rate MAP-2in HPC+O group decrease obviously, the statistics showedsignificant difference, P<0.05; N group、C group and HPC group almost no expression ofMAP-2.Conclusions:1．The effect study of hypoxic preconditioning on learning and memory in cerebralischemia-reperfusion mice.2．Cerebral ischemia-reperfusion injury can lead to different degrees of cognitivedysfunction in mice. 3．Hypoxic preconditioning can improve learning and memory ability of ischemiareperfusion in mice.4．Hypoxic preconditioning play a neuroprotective effect in reduced and neuronalapoptosis of cerebral ischemia-reperfusion injury in mice.5．Hypoxic preconditioning can reduce the positive expression rate of MAP-2,increase in hippocampal synaptic plasticity, enhancing the ability of learning and memory.This in-depth understanding of hypoxic preconditioning on cerebralischemia-reperfusion injury in the role of learning and memory protection is important. Atthe same time, provide an experimental basis for new strategies and science for theprevention and treatment of cognitive dysfunction after cerebral ischemia/hypoxia inclinic.