DISTRIBUTION AND LOCALIZATION OF NMDA RECEPTOR SUBUNIT-1 IN THE VISUAL-CORTEX OF STRABISMIC AND ANISOMETROPIC AMBLYOPIC CATS

ACTIVATION of NMDA (N-methyl-D-aspartate) receptors has recently been proposed as a prerequisite for the induction of experience-dependent m odification of visual cortical neurones seen during early postnatal de velopment. A new monoclonal antibody to the NMDA receptor subunit 1 (N MDA-R1) has been used to localize and compare the distribution of the receptors in the primary visual cortex of normal cats and those raised with either amblyopia induced by monocular optical blur or monocular esotropic strabismus. Although all three groups showed densest labelli ng in layers II-III, a comparison of immunopositive cells at any depth below the cortical surface showed a significantly lower frequency in strabismic and anisometropic cats than in normal cats, but a greater f requency in anisometropic cats that in strabismic animals. There appea rs to be no direct relationship between the expression of NMDA-R1 rece ptors and the level of excitability, binocularity or neuronal acuity k nown to exist in either of these two cat models of amblyopia, thus rai sing further questions as to the precise nature of the role of NMDA re ceptors in the processes of visual cortical plasticity.