CNQX blocks acidic amino acid induced depolarizations and synaptic components mediated by non-NMDA receptors in rat hippocampal slices.
6-Cyano-2,3-dihydroxy-7-nitro-quinoxaline (CNQX; FG 9065) is a new excitatory amino acid antagonist. In the spinal cord it has been reported to selectively block responses to acidic amino acids acting at receptors of the non-N-methyl-D-aspartate (non-NMDA) type. Here we report that in rat hippocampal slices bathed in Mg2+-free medium 10 microM CNQX reversibly blocks responses to alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA), quisqualate and kainate but not NMDA. The synaptic response evoked by low frequency stimulation of Schaffer collateral-commissural fibres in 1 mM Mg2+-containing medium is completely blocked by this concentration of CNQX. In contrast the synaptic response evoked in Mg2+-free medium is not fully blocked by CNQX. The CNQX-insensitive component is, however, abolished by addition of a selective NMDA antagonist. The use of CNQX has allowed for the first time selective synaptic activation of NMDA receptors in the hippocampus.
D000818:Animals; D005260:Female; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D007051:Ibotenic Acid / Q000031:analogs & derivatives / Q000502:physiology; D007608:Kainic Acid / Q000502:physiology; D010069:Oxadiazoles / Q000502:physiology; D011810:Quinoxalines / Q000502:physiology*; D016318:Quisqualic Acid; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D013569:Synapses / Q000187:drug effects* / Q000502:physiology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
D010069:Oxadiazoles; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D007051:Ibotenic Acid; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D016318:Quisqualic Acid; D007608:Kainic Acid