The network-selective actions of quinoxalines on the neurocircuitry operations of the rabbit retina

Brain Res. 1999 Jun 12;831(1-2):206-28. doi: 10.1016/s0006-8993(99)01448-1.


We examined the contribution of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxalole-4-propionic acid (AMPA)/kainate (KA) receptors to the light-responses of rabbit retinal neurons. In the outer retina, bath application of the AMPA/KA receptor antagonists 6,7-dinitro-quinoxaline-2,3-dione (DNQX) and 2,3,dihydroxy-6-nitro-7-sulfamoyl-benzo-f-quinoxaline (NBQX) blocked the light-responses of horizontal cells. Application of quinoxalines enhanced ON-bipolar cell light-responses, and was associated with a hyperpolarization of their resting potentials. In the inner retina, application of both AMPA/KA and NMDA antagonists to AII amacrine-like cells only partially blocked their light-responses. Their residual responses may reflect electrical coupling to neighboring ON-center cone bipolar cells, and can inhibit OFF-center ganglion cells. ON-sustained ganglion cells were highly sensitive to the quinoxalines, which reduced their light-evoked firing, while the firing of ON-transient cells remained as NMDA-mediated light-responses. Quinoxalines had differential effects on the firing rates of ON- and OFF-center ganglion cells: ON-cells were reduced, while OFF-cells were increased. In contrast, firing rates of ON-OFF ganglion cells were not excited by NBQX, and showed a recovered light-response mediated by NMDA receptors. The receptive field surround was lost in ganglion cells. For comparison, NMDA antagonists had only moderate effects on all ganglion cell light-responses. Our results indicate that NMDA and AMPA/KA receptors both contribute to ganglion cell light-responses. However, AMPA/KA receptors also significantly effect the light-response of neurons presynaptic to retinal ganglion cells, altering the observed pharmacology at the ganglion cell level.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Excitatory Amino Acid Antagonists / pharmacology
  • Light
  • Membrane Potentials / drug effects
  • Membrane Potentials / radiation effects
  • Nerve Net / drug effects*
  • Nerve Net / radiation effects
  • Quinoxalines / pharmacology*
  • Rabbits
  • Receptors, Glutamate / drug effects*
  • Receptors, Glutamate / radiation effects
  • Retina / drug effects*
  • Retina / radiation effects
  • Retina / ultrastructure
  • Retinal Ganglion Cells / drug effects
  • Retinal Ganglion Cells / radiation effects
  • Visual Pathways / drug effects*
  • Visual Pathways / radiation effects
  • Visual Pathways / ultrastructure
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / pharmacology


  • Excitatory Amino Acid Antagonists
  • Quinoxalines
  • Receptors, Glutamate
  • 2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
  • FG 9041
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid