RESUMO
The effect of lesionectomy depends on the reversibility of the epileptogenic changes in the perilesional cortex. We studied how the perilesional GABAergic neuronal changes are related to the effect of lesionectomy in the alumina cream-induced focal epilepsy model in cats. Sequential changes of GABAergic neurons and spike activities were measured after the micro-injections of alumina cream (AC). Alumina granulomas were excised 15 days and 40 days after the injections. At day 20 following the AC injection, GABAergic neurons were decreased 25 to 40% compared with those in the contralateral intact cortex. At day 40, a significant increase of spike activities occurred. GABA positive cells were decreased more than 50% compared with those in the contralateral cortex. At day 80, significant cell loss in perilesional cortex was demonstrated. The effect of lesionectomy was greater in the early excised group than in the late excised group. Decrease of GABAergic neuron was more severe in the late excised group compared to the early excised group. Our results indicate that more than 50% reduction of perilesional GABA neurons may be a critical point in epileptogenesis in this model. Lesionectomy alone prior to a 50% reduction in perilesional GABAergic neurons may be sufficient for seizure control. With these data it is still unclear whether these findings contribute to the choice between lesionectomy alone and lesionectomy with resection of the perilesional cortex. Further study is needed to understand the difference between the AC epilepsy model and human chronic epilepsy.