The role of N-methyl- d-aspartate receptors in synaptic plasticity of rat visual cortex in vitro: effect of sensory experience

Abstract

We examined the role of N-methyl- d-aspartate (NMDA) receptors in synaptic plasticity of visual cortex of light (LR) and dark (DR) reared adult rats in vitro. Layer IV stimulation resulted in field potentials in layer II/III, consisting of two excitatory postsynaptic potentials (EPSP) called EPSP1 and EPSP2. Tetanic stimulation induced long-term potentiation (LTP) in EPSP2 of both LR and DR visual cortices. NMDA receptor antagonist d, L-2-amino-5-phosphono-valeric acid (AP5) completely blocked the LTP of EPSP2 in DR visual cortex while it reduced slightly the extent of LTP of EPSP2 in LR ones. Another NMDA receptor antagonist ketamine blocked potentiation of EPSP1 as well as EPSP2 in both groups. Our findings demonstrate that dependency of LTP on NMDA receptors and/or sensitivity of these receptors to the antagonists are different in LR and DR animals.