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Synaptic transmission at the Schaffer-CA1 synapse is blocked by 6,7-dinitro-quinoxaline-2,3-dione. An in vivo brain dialysis study in the rat

Neuroscience Letters
Publication Date
DOI: 10.1016/0304-3940(89)90275-9
  • 6
  • 7-Dinitroquinoxaline-2
  • 3-Dione
  • Synaptic Transmission
  • Hippocampus
  • Brain Dialysis
  • Non-N- Methyl- D-Aspartateantagonist
  • Field Potential


Abstract 6,7-Dinitro-quinoxaline-2,3-dione (DNQX, FG 9041), a new non-N- methyl- d-aspartate (NMDA) glutamate receptor antagonist, has been reported to block non-NMDA receptor-mediated excitatory amino acidic responses in cultured neurons. We have perfused this compound in vivo through a dialysis fiber placed in the CA1 regions of anesthetized rats to test its effects on CA1 field-evoked potentials. Perfusions of 25–100 μM DNQX completely abolished field excitatory postsynaptic potentials (EPSP) and orthodromic population spikes (PS). This effect was dose-dependent and was reversed after washing with fresh K rebs-Ringer-bicarbonate. Antidromic population spikes and fiber volley potentials were unaffected by perfusions of DNQX up to 100 μM. On the contrary, perfusion of 50 μM d-2-amino-5-phosphonovalerate, a specific NMDA receptor antagonist, left unchanged both field EPSP and orthodromic PS. Results demonstrate that low-frequency transmission at the Schaffer collaterals-CA1 synapse is mediated by non-NMDA glutamate receptors.

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