Huanao Yicong Decoction Regulates The Synaptic Plasticity Of Alzheimer’s Disease By Targeting The PS/y-secretase/α-Nrxn 1 Pathway

First part:Objective:The overview of systematic review is used to evaluate the systematic review/meta-analysis of the existing traditional Chinese medicine(TCM)treatment for Alzheimer’s disease(AD).Method:Searched PubMed,Embase,Cochrane Library,Chinese Biomedical Literature Database,CNKI,Wanfang Database,and VIP Database,and select studies that meet the inclusion criteria.The publication is limited from the beginning of the database construction to December 14,2020.Two researchers independently screened the literature and extracted data with reference to the inclusion and exclusion criteria.Assessing the Methodological Quality of Systematic Reviews 2(AMSTAR-2)was used to evaluate the methodology quality of the included studies.The quality of the level of evidence for outcome measures is assessed by the Grading of Recommendations,Assessment,Development,and Evaluation(GRADE).Used a combination of qualitative and quantitative methods to illustrate the results.Qualitative research mainly describes the results of AMSTAR-2 and GRADE,and quantitative research is represented by forest plots.Result:A total of 20 systematic reviews/meta-analyses met the inclusion criteria.The main outcomes include:Activies Daily Living(ADL),Mini-mental State Examination(MMSE),Alzheimer’s Disease Assessment Scale-Cognitive section(ADAS-Cog),efficacy of TCM syndromes,TCM syndrome scores,adverse events Incidence,effective rate,Montreal Cognitive Assessment(MoCA),Hasegawa Dementia Scale(HDS),Clinical Dementia Rating(CDR).According to AMSTAR-2,2 studies were considered low quality and 18 studies were considered extremely low quality.According to GRADE,no high-quality evidence was found.Only the effectiveness,MMSE,and ADL of 3 studies were considered medium quality,and the remaining studies were considered low or very low quality.Among the degrading factors,the risk of bias in the original trial ranked first,followed by publication bias,inconsistency,and imprecision.None of the studies found escalation factors.Only two studies quantified the incidence of adverse events,and the quality of the evidence was very low.The results of 14 studies with total effective rate showed that the treatment group was significantly higher than that of the control group(OR=1.44;95%CI=1.29-1.62);the pooled results of 19 studies showed that the treatment group significantly improved the MMSE(WMD=1.19;95%CI=0.80-1.57);the pooled results of 16 studies showed that the treatment group and the control group had no significant difference in improving ADL(WMD=-0.19;95%CI=-0.92-0.54);3 studies show that the treatment group can significantly improve the TCM syndromes of AD patients(WMD=4.26;95%CI=3.22-5.30).The pooled results of 7 studies showed that the treatment combination control group had no statistically significant difference in improving AD AS-Cog(WMD=-0.96;95%CI=-2.12-0.21).Conclusion:The total effective rate of TCM or combined western medicine in the treatment of AD is higher than that of western medicine or placebo alone,and can effectively improve the cognitive function of patients.However,based on AMSTAR-2 and GRADE,it is found that the methodological quality and evidence quality of the existing systematic reviews/Meta-analysis is low.It is not yet able to provide strong recommendations.In addition,based on the existing evidence,it is impossible to evaluate the safety of TCM in the treatment of AD.In the future,more rigorous and high-quality systematic reviews/Meta analyses need to be carried out to provide more evidence support.Second part:Objective:To observe the effect of Huannao Yicong Decoction(HYD)on the synaptic plasticity of presenilin double gene knockout mice(PScDKO)by intervening the PS/γ-secretase/α-Nrxn 1 pathway.Method:Three-month-old PScDKO mice were randomly divided into 6 groups,including model Ⅰ group,model Ⅱ group,DAPT group,Huannao Yicong Decoction(HYD)low-dose group,HYD middle-dose group and HYD high-dose group,each with 16 mice.The C57 mice with the same genetic background were used as a control group.The control group and the model group I were given normal saline intragastrically,the DAPT group was given intraperitoneal injection of 5.0 mg/kg,and the model group Ⅱ was given intraperitoneal injection of the same amount of normal saline in the DAPT group.The HYD low,medium and high dose groups were given 1.7g/Kg,3.4 g/Kg,6.8g/Kg for intragastrically administered.It is administered once a day for 3 months.The Morris and platform jumping were used to observe the spatial learning and memory and memory retention,electrophysiological detection of excitatory postsynaptic potential long-term enhancement time,transmission electron microscopy to observe the morphology and number of synapses,HE staining and Nissl staining to observe hippocampal CA1 neuron morphology and Nissl body,enzyme-linked immunosorbent assay to detect the levels of y-secretase,APP,Aβ1-40,Aβ1-42,and immunoprecipitation method to observe The binding of α-Nrxn 1 to α-DG,Cstn 3,and Nxph 1.Western blotting and real-time PCR were used to detect the expression levels of α-Nrxn 1,α-DG,Cstn 3,Nxph 1,GluRδ2,and AchE.Result:Electrophysiological showed that the excitatory postsynaptic potential slope in the model group was significantly lower than that in the control group(P<0.05).After intervention,the duration of long-term potentiation in the high-dose group of TCM was longer than that in the model Ⅰ group(P<0.05).Transmission electron microscopy showed that the number of synapses in the HYD high-dose was significantly greater than that in the model group,and the post-synaptic compacts were darker in color.In the model group,the number of times of platform crossing,the distance ratio of the original platform quadrant and the time ratio of the original platform quadrant all decreased(P<0.05).The number of times of wearing the platform in the HYD low-dose was higher than that in the model group(P<0.05).The number of errors in the HYD low,medium and high dose groups of was significantly reduced(P<0.05).The hippocampus CA1 in the model group is morphologically disordered,and the abnormal morphology can be improved to a certain extent in each group.The cells in the hippocampal CA1 of each group were arranged more neatly,cell necrosis was not obvious,and Nissl bodies increased compared with the model group.Synaptic plasticity damage in PScDKO mice has nothing to do with Aβ deposition.PS function inactivation did not destroy the binding effect of α-Nrxn 1 and postsynaptic protein.The protein and mRNA expression levels of α-Nrxn 1,Nxph 1 and GluRδ2 in model mice were down-regulated(P<0.05),and the expression levels after medication were up-regulated(P<0.05).The inactivation of PS function resulted in the up-regulation of protein and mRNA expression levels ofα-DG,Cstn 3 and AchE(P<0.05),and the expression levels after medication all decreased to varying degrees(P<0.05).Conclusion:The extract of HYD may improve the abnormal synaptic plasticity of PScDKO by regulating the expression levels of α-Nrxn 1 pathway-related proteins and mRNA,thereby exerting an anti-AD therapeutic effect.