The effect of ketamine on synaptic transmission and synaptic plasticity in CA1 area of rat hippocampal slices

The effect of ketamine (1-100 µM), which has NMDA receptor antagonist properties, on synaptic transmission and long-term potentiation (LTP) in CAl area of rat hippocampus was examined in vitro. Field potentials were recorded in pyramidal cell layer following Schaffer collateral stimulation. Primed-burst stimulation (PEs) was used for induction of LTP. The amplitude of population spiks (PS) was used as a measure of LTP induction. The results showed that ketamine (1-100 µM) affected baseline synaptic transmission in a concentration-dependent pattern. Furthennore, ketamine application at a high concentration (50-100 µM) for a period of 20-30 min markedly blocked the induction of LTP, whereas lower concentrations of ketamine (1-10 µM) failed to block LTP. However, ketamine at a concentration of 20 µM affected NMDA-mediated LTP induction in a different pattern. It is concluded that the effect of ketamine on baseline synaptic transmission and LTP induced by a l00 Hz PBs depends on ketamine concentration.