The Influence Of Chronic Stress And The Impact Of Fluoxetine Intervention On Rats: Change Of Cognitive Function And Hippocampal Neural Cell Adhesion Molecule Expression

PartⅠChronic stess on rats:change of cognitive function and hippocampal neural cell adhesion moleculeObjectives:To investigate the influence of chronic restrain water-immersion stress on rats from the change of their cognitive function and hippocampal NCAM.Methods:1.Establishment of chronic restrain water-immersion stress model60 Normal adult male SD rats(180-200g),40 rats were random selected as stress group:restrained into water 1 hour per day for 3 weeks;20 rats as control group:normal feeding.2.Morris water-maze testAfter the 3weeks chronic restrain water-immersion stress,random select 10 rats from the stress group and the other 10 rats from the control group. Both 10 rats were given Morris water-daze test.Evaluate their cognitive function through escape latency3.Examination of rat hippocampal NCAM The 20 rats were given polyoxymethylene perfusion through Left ventricular.After perfusion their brain were taken out as specimens. Immunohistochemical staining was used to detect the NCAM around hippocampal area.4.Statistical methodsThe data were analyzed with SPSS software using mean±standard deviation said by t test.Results:Total 4 rats died of drowning and accidents such as anesthesia,all from stress group.The Morris water-daze test:1.escape latency:stress group 25.2±3.6s,control group 37.9±5.1s(p＜0.05,t=-4.76);The hippocampal NCAM:stress group 25.2±3.6 control group 37.9±5.1(P＜0.05,t=6.09).Conclusion:The chronic stress does harm to rat's cognitive function,the stress rats have less hippocampal NCAM than normal rats.The chronic stress can inhibit NCAM and may damage cognitive function in rats by doing that.PartⅡImpact of fluoxetine intervention on stress rats:change of cognitive function and hippocampal neural cell adhesion moleculeObjectives: To investigate the influence of fluoxetine intervention on stress rats from the change of their cognitive function and hippocampal NCAM.Methods:1.The left 26 stress rats were random divided into 2 groups:13 rats as fluoxetine intervened group and 13 rats as NS intervention group.The left 10 control rats were normal fed.2.Fluoxetine intervention for 3 weeks The fluoxetine group were given fluoxetine 10mg/kg through intraperitoneal injection.The NS intervention group were given the same dose NS through intraperitoneal injection.The total intervention time was 3 weeks. These two groups kept on being restrained into water 1 hour per day while intervention.The other 10 control normal rats were given the same dose NS through intraperitoneal injection.3.Morris water-maze testAfter the 3weeks chronic restrain water-immersion stress,all the left rats were given Morris water-daze test.Evaluate their cognitive function through escape latency4.Examination of rat hippocampal NCAMThe left rats were given polyoxymethylene perfusion through Left ventricular.After perfusion their brain were taken out as specimens. Immunohistochemical staining was used to detect the NCAM around hippocampal area.5.Statistical methodsThe data were analyzed with SPSS software using mean±standard deviation said by t test. Results:Total 4 rats died of drowning and accidents such as anesthesia,2 from fluoxetine intervention group and 2 from NS intervention group.The Morris water-daze test:escape latency:fluoxetine intervention group (n=13) 18.01±6.3s,normal control group(n=10) 5.35±2.0s,NS intervention group(n=13) 54.18±23.08s.Anova and SNK test result: there are significant statistical differences between these three groups. There were statistical differences between fluoxetine intervention group and the stress group without any intervention on escape latency.There also were significant statistical differences between NS intervention group and the stress group without any intervention on escape latency.The hippocampal NCAM:normal control group(n=10)38.6±2.57;fluoxetine intervention group(n=12) 22.0±2.84;NS intervention group(n=13)21.3±2.40.Anova and SNK test result:There are significant statistical differences normal control group and fluoxetine intervention group,and also between normal control group and NS control group.But the difference between fluoxetine intervention group and NS control group don't have Statistical significance.Conclusion:The fluoxetine intervention could improve cognitive impairment caused by the chronic stress.After the intervention the learning and memory function of the stress rats were improved.The fluoxetine intervention last for 3 weeks did not improve the low of rats hippocampus NCAM.