AMPA receptor properties at the synapse between retinal afferents and thalamocortical cells in the dorsal lateral geniculate nucleus of the rat

Abstract

The thalamocortical (TC) cells in dorsal lateral geniculate nucleus transfer signals from retinal afferents to the primary visual cortex. The excitatory retinal input to the TC cells is mediated by ionotropic receptors of the N-methyl- d-aspartate (NMDA) and non-NMDA type. In the present study the excitatory postsynaptic current (EPSC) mediated by non-NMDA receptors in this synapse was characterised by means of voltage-clamp recordings from TC neurons in rat thalamic slices. The specific alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist GYKI-53655 fully blocked the non-NMDA meditated EPSC, evoked by optic tract stimulation. The EPSC peak amplitudes were linearly related to the command voltage, suggesting that the receptor complex includes the GluR2 subunit. The EPSC amplitude and decay time increased during application of the desensitisation blocker, cyclothiazide, showing that the EPSC was partly controlled by fast desensitisation.