Influence Of BUSHENYIZHI Decoction On Learning-Memory Ability And Expression Of NGF In An AD Rat Model

ObjectiveTo investigate the effect of BUSHENYIZHI Decoction(BSYZD) on learning-memory ability,expression of Choline Acetyltransferase(ChAT) and nerve growth factor(NGF) in hippocampus CA1 of Alzheimer's Disease(AD) rat model established by injured with ibotenic acid(IBO) in nucleus basalis of Meynert(NBM).Method72 AD rats aged 3-month were randomly divided into six groups including normal group,AD model group,Hup-A group and BSYZD(low dose,middle dose, high dose) group.Rats of normal group were injected with physiologic saline in NBM,and rats of the other groups were injected with 10μg ibotenic acid (IBO) injection.Rats of the BSYZD groups were were orally administrated with BSYZD for 28 days.The postitive control drug was Huperxine A.After being treated for four weeks,we assayed the ability of cognition and memory abilities of all the rats by the test of Morris water maze(MWM),including Place Navigation Training and the Spatial Probe Test.After finishing 6-day's Morris water maze test,we randomly selected 4 rats in each group and then took out their whole brain after perfusion with 4%paraformaldehyde.The brains were embedded by paraffin and cut into pieces.The paraffin-sections were stained with Two-step immunohistochemistry method,and the data of positive cell number,size and average optical density for ChAT and NGF in hippocampus CA1 was recorded by the Leica image pattern analyser.All data were expressed as(?)±s,and statistic software of SPSS11.5 was operated to analysis all of the data.The 5 days data of Place Navigation Training was analyzed by Repeated Measures module;Average swimming time and distance of day 3 to day 5 was analyzed by One-way ANOVA statistics method, same as the data of Spatial Probe Test,positive cell number,size and average optical delnsity in hippocampus CA1.Results1.The Morris water maze test includes two parts:Place Navigation Training and the Spatial Probe Test.The results were expressed as follows:1)Place Navigation Training(1) Trend of the five-day changes:As time went on,the swimming time and distance were shorter gradually and shows a downward trend.It indicated that the position of the platform is a process of learning and memorizing which can be trained through a repeated way.(2) Comparisons between the six groups:In the period of day 3 to day 5,Compare with normal group,the swimming time and distance of rats in AD model group were longer significantly(P<0.01),which meant the AD rat model was established successfully.Compare with AD model group,the swimming time and distance of rats in Huperxine A group,BSYZD(low dose,medium dose) group were shorter significantly(P<0.01,P<0.05);the swimming time and distance of rats in BSYZD(high dose) group was shorter significantly(P<0.05).The result shows that all dose of BSYZD can improve the learning ability of AD rat model.2)Spatial Probe TestCompare with normal group,the time stayed in the fourth quadrant(the position of the platform) of AD model group was significantly shorter (P<0.01),and the times of crossing the situation of platform was reduced,which meant the AD rat model was established successfully.But AD model group,in both the time stayed in the forth quadrant and the times of crossing the situation of platform,shows no difference in Huperxine A group and all of the BSYZD group(P>0.05).2.The result of expression of ChAT in hippocampus CA1:Compare with normal group,the positive cell number,area and the optical density of AD model group were significantly reduced(P<0.01).That shows cholinergic nerve was injured in the AD model group.Compare with AD model group,the positive cell number of Huperxine A group and BSYZD(medium,high dose) group were increased,the average optical density of positive cell in Huperxine A group and BSYZD(low, medium dose) group were increased(P<0.05,P<0.01),the area of positive cell in BSYZD(high dose) was increased(P<0.01).It indicated that BSYZD can increase the expression of ChAT in the hippocampus CA1.3.The result of expression of NGF in hippocampus CA1:Compare with normal group,the area average optical density of positive cell of AD model group was increased(P<0.01),That shows the expression of NGF increased the AD model group.Compare with AD model group,the area of positive cell in Huperxine A group and BSYZD(low,medium) group were reduced,the cell number of positive cell in BSYZD(low dose) group was reduced(P<0.05,P<0.01).It indicated that BSYZD can reduced the expression of ChAT in the hippocampus CA1.The reason is speculated as the BSYZD improved the retrograde axoplasmic transport of NGF,which helped the cholinergic nerve terminals to absorb and transport more NGF to basal forebrain,and reduced the accumulation of NGF in hippocampus.ConclusionsBSYZD(low dose,middle dose,high dose) can improve the learning-memory ability of AD rat model and protect the cholinergic neurons to some extent. BSYZD was probably can improved the retrograde axoplasmic transport of NGF.It was suggested that BSYZD can raise the expression level of ChAT,and increase the synthesis of ach,improve the function of cholinergic neural system.And BSYZD probably could improve the retrograde axoplasmic transport of NGF,increased the content of NGF in the basal forebrain,and recover the injured cholinergic neurons.This may be a new mechanism for the BSYZD to improve the learning-memory impairment of AD.