New quinoxalinediones show potent antagonism of quisqualate responses in cultured mouse cortical neurons.

Two new quinoxalines, DNQX (6,7-dinitro-quinoxaline-2,3-dion = FG 9041) and CNQX (6-nitro-7-cyano-quinoxaline-2,3-dion = FG 9065), were tested as antagonists of excitatory amino acid responses in cultured neurons and brain slices. DNQX and CNQX showed potent competitive antagonism of quisqualate and kainate induced [3H]GABA release from cultured mouse cortical neurons with weaker effects on NMDA responses (Schild values for DNQX were 6.2, 5.9 and 5.4, respectively). Also in a model of excitatory amino acid induced 22Na efflux from striatal slices DNQX blocked responses to quisqualate and kainate more effectively than responses to NMDA.