Kainate receptor-mediated synaptic currents in mudpuppy inner retinal neurons reduced by D-O-phosphoserine.
1. The effects of D-O-phosphoserine (DOS) were examined on proximal neurons in the superfused mudpuppy retinal-eyecup preparation by measuring their synaptically evoked whole-cell currents with the use of patch-clamp electrodes. 2. DOS reduced the light-evoked excitatory postsynaptic potentials (EPSPs) of amacrine and ganglion cells. This suppression was present even though the center responses of both ON- and OFF-bipolar cells were unaffected by DOS. 3. When recordings were done under voltage-clamp conditions. DOS diminished the magnitude of light-evoked synaptic currents associated with a reduction in synaptic conductance. 4. To determine which acidic amino acid receptor mediated the network-selective action of DOS, various glutamate agonists were tested against this excitatory amino acid receptor (EAAR) antagonist. DOS blocked the depolarizing effects of kainate (KA), but not those of N-methyl-D-aspartate (NMDA) or quisqualate (QQ). Thus DOS was a selective KA antagonist, and KA receptors appear to be the dominant EAAR subtype that mediates synaptic inputs into the inner retina of the mudpuppy.
Coleman
P A
PA
Department of Physiology, University of Minnesota, Minneapolis 55455.
Miller
R F
RF
D000818:Animals; D008564:Membrane Potentials / Q000187:drug effects; D009338:Necturus maculosus; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D010768:Phosphoserine / Q000494:pharmacology*; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter / Q000187:drug effects*; D012160:Retina / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D012694:Serine / Q000031:analogs & derivatives*; D013569:Synapses / Q000187:drug effects*
D010768:Phosphoserine; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter; D012694:Serine