Anticonvulsant effect of eslicarbazepine acetate (BIA 2-093) on seizures induced by microperfusion of picrotoxin in the hippocampus of freely moving rats.

Eslicarbazepine acetate (BIA 2-093, S-(-)-10-acetoxy-10,11-dihydro-5H-dibenzo/b,f/azepine-5-carboxamide) is a novel antiepileptic drug, now in Phase III clinical trials, designed with the aim of improving efficacy and safety in comparison with the structurally related drugs carbamazepine (CBZ) and oxcarbazepine (OXC). We have studied the effects of oral treatment with eslicarbazepine acetate on a whole-animal model in which partial seizures can be elicited repeatedly on different days without changes in threshold or seizure patterns. In the animals treated with threshold doses of picrotoxin, the average number of seizures was 2.3+/-1.2, and average seizure duration was 39.5+/-8.4s. Pre-treatment with a dose of 30 mg/kg 2h before picrotoxin microperfusion prevented seizures in the 75% of the rats. Lower doses (3 and 10mg/kg) did not suppress seizures, however, after administration of 10mg/kg, significant reductions in seizures duration (24.3+/-6.8s) and seizure number (1.6+/-0.34) were found. No adverse effects of eslicarbazepine acetate were observed in the behavioral/EEG patterns studied, including sleep/wakefulness cycle, at the doses studied.

Seizures induced by in vivo latrunculin a and jasplakinolide microperfusion in the rat hippocampus.

The molecular basis for developing epilepsy remains under debate. It is hypothesized that increased excitatory synaptic activity might activate the N-methyl-D-aspartate receptor/Ca(2+) transduction pathway, which induces long-lasting plasticity changes leading to recurrent epileptiform discharges. To determine if these effects are caused by disruption of F-actin in the dendritic spines, we have perfused the hippocampus of conscious rats with the F-actin-depolymerizing agent latrunculin Aand the actin filament stabilizer jasplakinolide. Single perfusions of latrunculin Aand jasplakinolide decrease and increase picrotoxin seizure threshold, respectively. Repeated perfusions of both latrunculin Aand jasplakinolide induce epileptic seizures and a long-term increase in neuronal excitability. These results suggest that actin disruption might not be just a consequence but also a possible cause of epileptic seizures. We propose a new experimental model in rats to study the biochemical changes that might lead to chronic seizures and a method for testing new antiepileptic drugs.