Objective To observe the effect of over-expressed amyloid procursor protein(APP) gene on the cholinergic receptor binding and the ChAT activity in human neuroblastoma cell line SH-SY5Y.Methods SH-SY5Y cells were transfected with pCMV695 plasmid containing wild type human APP695 gene by Lipofectamine 2000 method.The expression of APP was detected by Western blot.A? contents were test by ELISA assay in over-expression SH-SY5Y cell clones(SH-SY5Y-APP).The special binding of muscarinic and nicotinic cholinergic receptors in those A?-overproducing cell clones was determined by radio-ligand binding method.The cholinergic acetyl transferase(ChAT) activity was assayed by radiao-immunoassay.Results No evident morphologic changes of cytotoxicity were detected after transfection.When A? production was 2～2.6 times as much as that of normal cells,muscarinic receptor binding was decreased from 18.5 % to 21.9 %(P