Effects of ketamine on synaptic transmission and long-term potentiation inlayer II/III of rat visual cortex in vitro

The effects of ketamine, which has NMDA receptor antagonist properties, on synaptic transmission and long-term potentiation in layer II/III of adult r at visual cortex were examined in vitro. Field potentials were recorded in layer II/III following layer IV stimulation. Primed-burst stimulation was u sed for induction of long-term potentiation. Stimulation of layer IV result ed in a two-component response in layer II/III, a population excitatory pos tsynaptic potential1 (EPSP1) and a population excitatory postsynaptic poten tial2 (EPSP2). DL-2-Amino-5-phosphono-valeric acid (AP5), a competitive NMD A receptor antagonist, reduced the amplitude of the population EPSP1 while ketamine increased the amplitude of the population EPSP2. The results showe d that primed-burst stimulation induced long-term potentiation in layer II/ III of the visual cortex in vitro. Preincubation for 30 min with AP5 (25-10 0 mu M) reduced the extent of long-term potentiation of the population EPSP 2 and blocked the induction of long-term potentiation of the population EPS P1. When ketamine (100-200 mu M) was present for 30 min prior to tetanic st imulation, it blocked the induction of long-term potentiation of the popula tion EPSP1 and reduced the extent of long-term potentiation of the populati on EPSP2. We conclude that ketamine can interfere with synaptic transmissio n in the visual cortex. Primed-burst stimulation is an effective protocol f or neocortical potentiation. NMDA receptors are involved in the induction o f long-term potentiation by primed-burst stimulation of the population EPSP 1 and population EPSP2 in adult rat visual cortex in vitro. (C) 2000 Elsevi er Science B.V. all rights reserved.