Study On Effect Of XNY On Expression Of Aβ And Aβ-Degrading Enzyme NEP In Brain Of APPswe/PS1ΔE9Double Transgenic Mice

Objectives Through researching gene and protein expression of the beta amyloidprotein(A beta) and its degradation enzyme Neprilysin(NEP), this topic studied the effectof Traditional Chinese medicine compound XNY on expression of Aβ and Aβ-DegradingEnzyme NEP in Brain of APPswe/PS1ΔE9double transgenic mice, and meanwhileanalyzed the mechanism of Traditional Chinese medicine XNY from the perspective ofSenile dementia theory of TCM.Methods The mice were divided into normal control group, model group, westernmedicine control group, XNY high-dose group, XNY middle-dose group and XNY low-dose group. Then we observed the spatial learning and memory ability of six groups ofmice by using Morris water maze, detected the expression of senile plaques in the braintissue of six groups of mice by using immunohistochemical method, detected theexpression of NEPmRNA in the brain tissue of six groups of mice by real-timefluorescent quantitative PCR technique, and observed the expression of NEP protein inthe brain tissue of six groups of mice by Immune protein imprinting Western blotsmethod. All the experimental results were expressed as a mean standard deviation(x±s),the comparison between groups using single factor analysis of variance(one-wayANOVA), with statistical significance(P<0.05), with statistical significance(P<0.01).Results The SPF75healthy male three months double transgenic dementia mice and15male with normal mice were selected as the research objects.The results of Morriswater maze showed that in the aspect of swimming duration，the model group wasobviously higher than the normal control group, while the western medicine controlgroup and XNY high-dose group was obviously lower than model group, with statisticalsignificance(P<0.05). In the aspect of the fourth quadrant duration, the model group wasobviously lower than the normal control group, while the positive control group, XNYhigh-dose group and XNY middle-dose group were obviously higher than the modelgroup, with statistical significance(P<0.05). The results of immunohistochemical methodshowed that under a microscope senile plaques was brown material to be amyloid, andwere widely distributed in the hippocampus and cortex of brain tissue in mice. In theaspect of the number of senile plaques, model group was most in all groups. By thestatistics, in the aspect of the acumulative optical density value of senile plaques in braintissue in mice, from high to low in turn was the model group, XNY low-dose group,XNY middle-dose group, XNY high-dose group and the positive control group, while thepositive control group and XNY high-dose group were obviously lower than model group,with statistical significance(P<0.01).The results of real-time fluorescent quantitative PCR technique showed that in the aspect of the expression content of NEPmRNA in the braintissue of mice, from high to low in turn was the normal control group, the westernmedicine control group, XNY high-dose group, XNY middle-dose group, XNY low-dosegroup and the model group, while the normal control group was obviously higher thanthe model group, with statistical significance(P<0.01), the western medicine controlgroup and XNY high-dose group were obviously higher than the model group, withstatistical significance(P<0.01), but there was no statistical significance between XNYmiddle-dose group and the model group（P>0.05）, there was no statistical significancebetween XNY low-dose group and the model group（P>0.05）, there was no statisticalsignificance between the western medicine control group and XNY high-dose group（P>0.05）, but there were statistical significance among three different doses of XNYfrom high to low（P<0.05）. The results of Immune protein imprinting Western blotsmethod showed that the expression content of NEP protein in the brain tissue of mice,from high to low in turn was the the normal control group, the western medicine controlgroup, XNY high-dose group, XNY middle-dose group, XNY low-dose group and themodel group, while the normal control group was obviously higher than the model group,with statistical significance(P<0.01), the western medicine control group, XNY high-dosegroup and XNY middle-dose group were obviously higher than the model group, withstatistical significance(P<0.05), but there was no statistical significance between XNYlow-dose group and the model group（P>0.05）.Conclusions Traditional Chinese medicine compound XNY can effectively improvedthe cognitive function and improved the ability of learning and memory of alzheimer’sdisease model mice, meanwhile lower the deposits of senile plaques in hippocampus andcortex of brain tissue in mice and raised the neutral peptide enzyme gene and proteinexpression in the brain tissue.The mechanism of XNY may be related to the interventionof amyloid protein metabolism, and the promotion of the activity of the brain peptideenzyme in neutral, which accelerating the degradation of toxic proteins in the brain orindirect inhibition of its formation.