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

Inhibition of the subthalamic nucleus (STN) has been shown to suppress seiz ures in different animal models of epilepsy. The aim of this study was to e xamine 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 pallid us or the ventral pallidum, by local injections of a GABA(A) antagonist, su ppressed absence seizures. Conversely, inhibition of the ventral pallidum b y a GABA(A) agonist aggravated absence seizures. Furthermore, the antiepile ptic effects of intrapallidal injections of a GABA(A) antagonist were corre lated with a decrease of extracellular levels of glutamate in the substanti a nigra. Our results show that both the globus pallidus and the ventral pal lidum exert a modulatory influence on absence seizures and suggest that the se effects are mediated through the STN. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.