L-689560 is a potent N-methyl-D-aspartate (NMDA) receptor antagonist at the GluN1 glycine binding site. L-689560 is widely used as a radiolabeled ligand in binding studies and used for study the roles of NMDA receptors in normal neurological processes as well as in diseases^[1][2]. In Vitro: L-689560 is a 2-carboxytetrahydroquinoline antagonist^[2]. In Vivo: L-689560 (1 mg/kg, ip) significantly reduces the neuroprotective effect of glycine after glycine receptors and the channel activity of NMDA receptors (NMDARs) are suppressed. L-689560 blocks glycine-induced increase of Akt phosphorylation in the MCAO model^[1]