CNQX blocks acidic amino acid induced depolarizations and synaptic components mediated by non-NMDA receptors in rat hippocampal slices

Neurosci Lett. 1988 Jun 29;89(2):182-6. doi: 10.1016/0304-3940(88)90378-3.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Female
  • Hippocampus / drug effects*
  • Hippocampus / physiology
  • Ibotenic Acid / analogs & derivatives
  • Ibotenic Acid / physiology
  • Kainic Acid / physiology
  • Oxadiazoles / physiology
  • Quinoxalines / physiology*
  • Quisqualic Acid
  • Rats
  • Receptors, N-Methyl-D-Aspartate
  • Receptors, Neurotransmitter / physiology*
  • Synapses / drug effects*
  • Synapses / physiology
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid


  • Oxadiazoles
  • Quinoxalines
  • Receptors, N-Methyl-D-Aspartate
  • Receptors, Neurotransmitter
  • Ibotenic Acid
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
  • Quisqualic Acid
  • Kainic Acid