Objective To investigate the changes of expression of N-methyl-D-aspartate receptor(NMDAR)and mitogen activated protein kinase(MAPK)in Alzheimer disease(AD)rat model. Methods AD rat model was established by injection of amyloid-beta protein 1-40 1?l(10 g/L)into hippocampus of rat.NMDAR-mRNA and MAPK protein were immunostained by in situ hybradization histochemistry and immunohistochemistry respectively.Learning and memory ability,LTP were determined by Morris water maze and electrophysiological methods respectively. Results The escape latent was prolongated in Alzheimer rats two weeks after injection of A? than in control rats and in rats before the injection of A?(P