This study was aimed at investigating the effects of lamotrigine (LTG) on e
lectrically evoked field excitatory postsynaptic potentials (fEPSP) and pop
ulation spikes in the CA1 hippocampal region of guinea pigs. The concentrat
ion response curves showed different actions of LTG on fEPSP and on populat
ion spikes. The data are in contrast to previous findings that suggest the
drug acts primarily on presynaptic sites via a blockade of the release of e
xcitatory amino acids, In the range of therapeutic plasma levels, synaptic
transmission was not affected. Copyright (C) 2000 S. Karger AG, Basel.