Pre- and postsynaptic effects of baclofen in the rat hippocampal slice.

CA1 pyramidal cells responded to baclofen with a hyperpolarization. This response was found in the apical and basal dendrites and, like the hyperpolarizing response of the dendrites to GABA, appeared to be Ca2+-dependent since it was blocked or reduced by intracellular injection of EGTA or extracellular application of cadmium. Baclofen also reduced the excitatory and inhibitory postsynaptic potentials produced by stimulation of the Schaffer collaterals. The pre- and postsynaptic effects on the synaptic waveform could be distinguished.