Dependence of retinogeniculate transmission in cat on NMDA receptors.
1. We have examined the possibility that N-methyl-D-aspartate (NMDA) receptors may be involved in the visual response of relay cells in the cat dorsal lateral geniculate nucleus (dLGN). The selective NMDA receptor antagonists D-2-amino-5-phosphonovalerate (APV) and 3-[(+/-)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid (CPP) have been iontophoretically applied to X and Y cells in the dLGN and their effects on the visual response to a light spot flashed within the receptive field center determined. 2. The antagonist effects were assessed at ejection current levels producing a selective blockade of the responses to iontophoretically applied NMDA with respect to those elicited by the non-NMDA receptor agonists quisqualate and kainate. These selective effects were determined in an experimental paradigm where the visual response and responses to NMDA and the non-NMDA receptor agonists were compared in the same test run. The data refer to a total population of 52 cells (28 X, 24 Y). 3. Application of APV abolished or greatly reduced the visual responses of both X and Y cells. The mean percentage reduction in the visual response for the X cells studied was 59 +/- 10% (SE; n = 7) and for the Y cells 66 +/- 8% (SE; n = 11). Both the early onset transient and the sustained component of the visual response to the flashed stimulus were equally affected. 4. The antagonist CPP produced a similar pattern of effect to APV, substantially reducing or abolishing the visual response in both X and Y cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Sillito
A M
AM
Department of Visual Science, Institute of Ophthalmology, London, United Kingdom.
Murphy
P C
PC
Salt
T E
TE
Moody
C I
CI
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology*; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D002415:Cats; D005260:Female; D005829:Geniculate Bodies / Q000187:drug effects / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology*; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D012160:Retina / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*
D000927:Anticonvulsants; D010879:Piperazines; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D015763:2-Amino-5-phosphonovalerate; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid