ABSTRACT
BACKGROUND:Previous studies have demonstrated that transplanted neural stem cells can survive and proliferate in the brain of Alzheimer disease(AD)rats,however,it is poorly understood whether it can rebuild the nerve tracts by substituting the injured or dead neurons and improve learning and memory abilities.Synaptophysin is one of the important markers of synaptic rebuilding.OBJECTIVE:To observe the effects of neural stem cell transplantation on synaptophysin expression in hippocampus and learning and memory abilities of AD rats.METHODS:Sprague Dawley rats were randomly divided into the normal control,AD model,2-week-transplantation and 4-week-transplantation groups.All rats were established AD models except that in the normal control group.Neural stem cells were isolated from the dentate gyrus of hippocampus of newborn rats,labeled with Hoechst33258,and then transplanted into CA1 region of hippocampus of rats in the 2-week-transplantation and 4-week-transplantation groups.The behavioral testing in the rats was performed using Y-maze trial.Nissl staining and synaptophysin immunohistochemistry were detected after the rats were sacrificed.The same volume of stroke-physiological saline solution was injected into rats in the AD models group using the identical methods.There was no treatment in the normal control group.RESULTS AND CONCLUSION:①The cells number in the hippocampal CA1 region of the 2-week-transplantation and 4-week-transplantation groups were increased than that of AD model group,but were still less than that of the normal control group(P ＜ 0.05).There was no significantly difference between the absorbance values of 2-or 4-week-transplantation group and control group(P ＞ 0.05).②The absorbance values of the 2-week-transplantation and 4-week-transplantation were significantly greater than that of the control and AD model groups(P ＜ 0.05).③The learning and memory abilities in 2-and 4-week-transplantation group enhanced obviously and their correct reaction rates improved evidently,which was found statistically significant difference from AD model group(P ＜ 0.05),while no statistically significant difference from control group(P ＞ 0.05).The transplanted neural stem cells may promote the synaptic rebuilding and improve learning and memory abilities in AD rats.