Abstracts

There is significant controversy regarding whether the brain damage associated with recurrent seizure activity in temporal lobe epilepsy is progressive or not. Moreover, until the present moment, no study has addressed whether seizure-related brain damage contributes for increased neurodegeneration in long term epilepsy. In this study we investigated the morphological alterations associated with long term recurrent seizure activity in old rats with epilepsy. The pilocarpine model of epilepsy was induced in Wistar rats (60 days old) by the administration of pilocarpine hydrochloride (350 mg/kg). After 5 hours of pilocarpine-induced status epilepticus (SE), the animals received an injection of diazepam (5 mg/kg) in order to reduce mortality. Surviving rats were monitored 24h a day, until 15 months of life for quantification of seizure frequency. Animals were then sacrificed, and had their brains removed for histological examination using hematoxylin-eosin, congo red, cresil violet, periodic acid-schiff and Masson staning. The mean frequency of seizures was of 4 to 5 per week. The time for first spontaneous seizure had not relationship with the frequency of seizures. The behavioral characteristics of seizures did not change with aging. The histological analysis showed no signal of additional brain degeneration in old rats with epilepsy, when compared with age-matched controls. Morphological alterations found in old rats with epilepsy do not differ from those reported in the literature for young rats. Our data suggest that recurrent seizure activity does not induce additional neurodegenerative processes in the old brain. (Supported by CNPq CAPES FAPESP.)