BETA-AMYLOID RELATED PEPTIDES EXERT DIFFERENTIAL-EFFECTS ON [H-3] MK-801 BINDING TO RAT CORTICAL

THE effects of beta-amyloid protein 140 (beta AP 140), substance P (SP ), and the amidated and carboxylic acid C-terminated forms of the SP h omologous beta AP fragment 25-35 (beta AP 25-35-NH2 and beta AP 25-35- COOH) were studied on [H-3]MK-801 binding to the rat brain NMDA recept or cation channel. All peptides gave dose-dependent enhancements of [H -3]MK-801 binding stimulated by low glycine. beta AP 25-35-COOH, but n ot beta AP 25-35-NH2produced an inhibition of [H -3]MK-801 binding sti mulated by high glycine in the presence of either low or high glutamat e. Low glutamate-stimulated [H-3]MK-801 binding was also inhibited by SP but not by beta AP 1-40. It is concluded that beta AP related pepti des exert differential effects on the NMDA receptor complex at the gly cine and possibly also the glutamate recognition sites.