Effects of Soybean Isoflavones on Cognitive Ability and Cholinergic System in AD Model Rats

Objective To investigate the effects of soybean isoflavones on cognitive ability and cholinergic system of Alzheimer's disease(AD) model rats.Methods Thirty healthy male SD rats were randomly divided into sham operation group,model group and SIF group,and each group included 10 rats.The regulated dose medicine was given to the SIF group by IG daily for 14 days before Aβ injection,while sham operation group and model group were given equivalent of 0.5% CMC-Na.The learning and memory abilities of rats were assessed with Morris Water Maze behavioral test on the 7th day after Aβ injection,then the pathological change in rats' hippocampus was observed and the activities of ChAT and AchE in hippocampus were examined by colorimetric method.Results 1.Compared with the sham operation rats,the abilities of learning and memory were lowered significantly(P0.01) in model rats,while in the rats of SIF group,it was found that their learning and memory abilities were improved(P0.05),as compared with the model rats.2.hippocampal in sham operation group showed that hippocampal pyramidal cell lined up in order,uniformity,and cellular structure was integrity with normal morphous;the hippocampal in model group showed that the number of hippocampal pyramidal cell was much more smaller and derangement with unclear construction,some nucleus were pyknosis and anachromasis;hippocampal in SIF group showed cell lined up most in order,and cellular structure was almost normal.3.Compared with sham operation group,the ChAT activity in hippocampus of modle group,decreased significantly(P0.05),but there was no significant change in AchE activity in hippocampus of modle group though a little enhancement appeared(P0.05);The ChAT activity of hippocampus in SIF group was much higher than that in model group(P0.05),but there was no obvious difference in AchE activity hippocampus between two groups(P0.05).Conclusions SIF can improve cognitive ability in AD model rats and enhance the ChAT activity of brain tissue,suggesting SIF may be related to increase synthesis of the neurotransmitter acetylcholine.