Evidence for the involvement of the pallidum in the modulation of seizures in a genetic model of absence epilepsy in the rat

Inhibition of the subthalamic nucleus (STN) has been shown to suppress seizures in different animal models of epilepsy. The aim of this study was to examine the role of the pallidal inputs to the STN in the control of absence seizures in a genetic model in the rat. Disinhibition of the globus pallidus or the ventral pallidum, by local injections of a GABA(A) antagonist, suppressed absence seizures. Conversely, inhibition of the ventral pallidum by a GABA(A) agonist aggravated absence seizures. Furthermore, the antiepileptic effects of intrapallidal injections of a GABA(A) antagonist were correlated with a decrease of extracellular levels of glutamate in the substantia nigra. Our results show that both the globus pallidus and the ventral pallidum exert a modulatory influence on absence seizures and suggest that these effects are mediated through the STN. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.