Suppression of limbic motor seizures by electrical stimulation in thalamic reticular nucleus

Abstract

Kindling is a model of temporal lobe epilepsy in which repeated electrical stimulations in limbic areas lead to progressive increase of seizure susceptibility, culminating in generalized convulsions and the establishment of a permanent epileptic syndrome. We studied here the effect of stimulations in the thalamic reticular nucleus (TRN) on the development of seizures and hippocampal hyperexcitability in kindling elicited from the ventral hippocampus in rats. Animals given 12 kindling stimulations per day with 30-min intervals for 4 consecutive days developed generalized convulsions on day 4. Stimulations in TRN delivered simultaneously with those in the hippocampus induced marked suppression of seizure generalization. Similarly, the number of generalized seizures and the duration of behavioral convulsions were reduced when rats subjected to 40 kindling stimulations with 5-min intervals during about 3 h were costimulated in the TRN. The anticonvulsant effect of TRN costimulation was detected also when rats were test-stimulated in the hippocampus at 24 h and 2 and 4 weeks after the initial 40 hippocampal stimulations. Our data provide the first evidence that TRN stimulations can act to suppress limbic motor seizures in hippocampal kindling and suggest a new approach for seizure control in temporal lobe epilepsy.