ABSTRACT
Objective To investigate the changes and the significance of the number of nerve cells and the expression of the postsynaptic density tyrosine kinase(Fyn) in the hippocampus of the rat whose spatial learning and memory function was enhanced by chronic multiple stress. Methods Thirty-nine adult rats were randomly divided into three groups: multiple stressed,single stressed and control group.Rats in the multiple stressed group were irregularly and alternatively exposed to the situation of vertical revolve,sleep expropriate,restraint(6h/d),and night illumination for 6 weeks,to preparate chronic multiple stressed model.Rats in the single stressed group were exposed to restraint only for 6 weeks,6h/d.After that,the performance of spatial learning and memory of all rats was measured using Morris water maze.Nerve cells in different subfields of the hippocampus were observed using Cresyl violet method and counted regardless of size or shape.The expression of Fyn protein and the level of Fyn mRNA in the hippocampus of rats were detected by immunohistochemical method and RT-PCR technique respectively. Results Compared with control group,the performance of spatial learning and memory of rats was increased in multiple stressed group and decreased in single stressed group((P