Topiramate depresses carbachol-induced plateau potentials in subicular bursting cells

Intracellular recordings were made in an in vitro slice preparation to esta blish whether the antiepileptic drug topiramate reduces the depolarizing pl ateau potentials (PPs) induced in the rat subiculum by intracellular pulses of depolarizing current, in the presence of the cholinergic agonist carbac hol (CCh, 70-100 mu M). PPs lasted up to about 2s, and disappeared during a pplication of the muscarinic receptor antagonist atropine. Topiramate (10-1 00 mu M, n = 22 neurons) decreased and eventually abolished in a dose-depen dent manner these PPs, even when the function of excitatory amino acid and GABA(A) receptors was blocked. Hence, topiramate depresses muscarinic recep tor-dependent PPs in the rat subiculum, thus suggesting that this form of e xcitation may represent a target for the mechanism of action of this antiep ileptic compound. NeuroReport 11:75-78 (C) 2000 Lippincott Williams & Wilki ns.