Abstracts

In humans, the long term consequences of chronic epilepsy cannot be evaluated in the absence of antiepileptic drugs. To address this issue, we studied the evolution of untreated seizures and the influence of aging in chronic epileptic rats. Male Wistar rats were submitted to the pilocarpine model of epilepsy. Surviving animals were observed 24h/day until death or by 16 months. Aged rats were submitted to electroencephalographic recordings and echo-cardiogram evaluation. Surviving animals were perfused at the age of 16 months and the brains were processed for histological study. Deceased rats before the age of 16 months were submitted to necropsy and hystopathological examination of internal organs. In chronic epileptic rats, the seizure frequency showed a great oscillation until the 11th month. After that period, experimental rats showed 4-5 seizures per week until death. EEG recordings of aged animals showed constant epileptic activity with a higher number of spikes when compared to young experimental rats. Despite the constant epileptiform activity, the frequency of behavioral seizures in aged animals was similar to that observed in young epileptic rats. Aged control rats did not presented any EEG abnormality. Aged epileptic and control rats showed the same abnormalities in the echo-cardiogram evaluation. Aged experimental rats showed more exuberant histological alterations of the hipocampal formation, including cell loss, gliosis and axonal sprouting, when compared to young rats. Finally, the experimental group showed a higher mortality rate when compared to control group. Aged epileptic rats showed a discrepancy between EEG and behavioral manifestations, in addition to a progressive neuronal damage and reorganization. Epileptic animals showed a higher mortality rate that was not related with cardiac dysfunctions. (Supported by CNPq, CAPES, FAPESP, PRONEX)