Endogenous indoles as novel polyamine site ligands at the N-methyl- d-aspartate receptor complex

High-throughput ligand displacement screens of a series of endogenous indoles revealed that tryptamine, serotonin and 5-methoxytryptamine readily displace [ 3H]spermidine and [ 3H]MK-801 from their respective binding sites in rat brain homogenate. These data, coupled with their potent inhibition of spermidine-potentiated [ 3H]MK-801 binding, suggest that certain endogenous indoles may act as ligands to one or more polyamine binding sites in the brain, including those on the N-methyl- d-aspartate receptor complex.