RESUMO
A study was designed to develop a measure of both acute and chronic effects of THC administration on memory in the rat. Errors in an 8-arm radial maze, before and after two delay intervals (5 s and 1 h, introduced between the fourth and the fifth arm choice), constituted the principal dependent measures. The first experiment involved testing the animals shortly after administration of 1.25 mg/kg THC. The drug did not affect performance in the pre-delay tests, although a significant effect was observed after the 5-s delay but not after 1-h delay. In the second experiment, 5 mg/kg THC or saline were administered 6 days/week for 90 days. Testing was conducted 18 h after each drug administration. During chronic administration the pre-delay performance did not differ between groups but the post-delay performance of the THC group deteriorated in a gradual manner, relative to their controls, in both the 5-s and 1-h delay conditions. After discontinuation of drug administration, the differences between groups reversed only after 30 days. The results provided evidence that both acute and chronic administration of THC affected working-memory in the radial arm maze test, although it did not interfere with the general cues of the task (reference memory). Chronic drug effects on memory were reversible after prolonged abstinence. Thus, the 8-arm radial maze task proved to be a useful measure of THC effects on memory and could be further used to investigate more thoroughly the mechanisms involved in such drug effects.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Aprendizagem por Discriminação/efeitos dos fármacos , Dronabinol/farmacologia , Rememoração Mental/efeitos dos fármacos , Orientação/efeitos dos fármacos , Animais , Masculino , Atividade Motora/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Tempo de Reação/efeitos dos fármacos , Retenção Psicológica/efeitos dos fármacosRESUMO
Male Wistar rats were subjected to pilocarpine-induced status epilepticus and allowed to recover. After reaching the chronic state with spontaneous seizures they were tested in an 8-arm radial maze. During learning trials, epileptic rats made significantly more errors than controls. Even in the last trials epileptic rats did not improve their performance, indicating severe learning disability. These results suggest that spontaneous seizures after pilocarpine-induced status epilepticus are a useful model for studying the learning and memory impairment detected in some cases of symptomatic epilepsy.
Assuntos
Comportamento Animal , Aprendizagem , Memória , Estado Epiléptico/fisiopatologia , Animais , Encéfalo/fisiologia , Masculino , Pilocarpina , Ratos , Ratos Endogâmicos , Estado Epiléptico/induzido quimicamenteRESUMO
Male Wistar rats were subjected to pilocarpine-induced status epilepticus and allowed to recor. After reaching the chronic state with spontaneous seizures they were tested in an 8-arm radial maze. during learning trials, epileptic rats made significantly more errors than controls. Even in the last trials epileptic rats did not improve their performance, indicating severe learning disability. These results suggest that spontaneous seizures after pilocarpine-induced status epilepticus are a useful model for studying the learning and memory detected in some cases of symptomatic epilepsy