The Effect Of Electro-acupuncture On P35/P25-Cyclin-Dependent Kinase 5-Tau Phosphorylation In Hippocampus Of Alzheimer’s Rats

Objective:To explore the improvement of cognitive impairment in AD model rats by electroacupuncture.And clear the effect of electro-acupuncture on“P35/P25-Cyclin-dependent Kinase 5（CDK5）-Tau phosphorylation”signal pathway in AD model rats.Finally,the mechanism of electroacupuncture in preventing and treating AD will be further studied.Methods:Firstly,fifty male adult Sprague-Dawley（SD）rats were randomly saperated into 4 groups（according to a random number table）:control,sham,model and the electroacupuncture treatment group（n=12）.The bilateral hippocampus of rats were injected with Aβ_25-35（1g/L）to make AD model（10μL on each side）.The normal saline with equal amount was adopted in the sham group at the same position.The rats of treatment group were treated with acupuncture at“Baihui”and“Shenshu”acupoints and connected with electroacupuncture apparatus for electroacupuncture intervention,once per day for ten days.Then the cell morphology in hippocampus of each group was compared by HE.Meanwhile,two semi-quantitative assays（Immunohistochemical staining and Western Blot）were used to identify the expression of P35/P25,CDK5 and Tau5 in the hippocampus of each group.At the same time,the expression levels of Tau[pS199]and Tau[pS202]were also measured by Western Blot.In addition,immunofluorescence and co-immunocoprecipitation were used to confirm the interaction of P35/P25 and CDK5 in the hippocampus of rats.Finally,all the results were analyzed by SPSS,Image J and Graph pad software.Results:Electroacupuncture can effectively shorten the escape latency and length of the AD rats（^#P<0.05）,and improve their spatial exploration ability（^#P<0.05）.The results of HE and immunohistochemistry staining showed that no significant change in the cell morphology among all group.And P35/P25,CDK5 and Tau5 proteins were all present in the cytoplasm.Combined with Western Blot and Immunohistochemical results,it can be seen that the expression levels of P35/P25,CDK5,Tau[pS199]and Tau[pS202]in the hippocampus of rats in the model group were higher than those in the controls and shams（^*P<0.05,^@P<0.05）.After electroacupuncture treatment,the increased expression were significantly inhibited（^#P<0.05）.However,there was no significant difference about Tau5 protein levels among the groups（P>0.05）.Additionally,the results of Immunofluorescence double labeling staining showed that P35/P25 and CDK5 were co-located in the hippocampus.At the same time,P35/P25and CDK5 had an interaction in the hippocampus tissues among all groups in the co-immunoprecipitation.And the combination of P25 and CDK5 was more significant than P35 and CDK5.Specially,the interaction in the model group was significantly higher than that in the sham and control group.Surely,we observed that the intensity of the interaction between the two decreased after electroacupuncture treatment.Conclusion:1.Electroacupuncture stimulation can significantly correct cognitive impairment in AD model rats.2.Electroacupuncture may delay the occurrence and development of AD by affecting P35/P25-CDK5-Tau phosphorylation signal pathway.3.P35/P25 and CDK5interact to some extent in rat hippocampal tissues,especially in the model group.And the interaction can be interfered by electroacupuncture.