EFFECTS OF FELBAMATE ON MUSCARINIC AND METABOTROPIC-GLUTAMATE AGONIST-MEDIATED RESPONSES AND MAGNESIUM-FREE OR 4-AMINOPYRIDINE-INDUCED EPILEPTIFORM ACTIVITY IN GUINEA-PIG OLFACTORY CORTEX NEURONS IN-VITRO

The effects of the anticonvulsant agent felbamate (FBM) were examined on muscarinic and metabotropic-glutamate receptor agonist-induced resp onses and chemically induced epileptiform activity, in guinea pig olfa ctory cortex slices in vitro. FBM (100-500 mu M) had little effect on neuronal membrane proper ties and on postsynaptic potentials evoked by electrical stimulation of lateral olfactory tract terminals, whereas it reduced the duration of presumed Ca++ spikes induced by intracellul ar Cs+ loading. In contrast, the muscarinic receptor agonist oxotremor ine-M (10 mu M) or the metabotropic glutamate receptor agonist 1-amino cyclopentane-1S-3R-dicarboxylic acid (10 mu M) induced a sustained mem brane depolarization with repetitive firing, an increase in input resi stance and the appearance of a slow poststimulus afterdepolarizing pot ential. These effects were reversibly reduced in the presence of FBM ( 100-500 mu M).