Audiogenic seizures last only for half a minute in average, suggesting that the interruptions of seizures are probably not due to exhaustion. Systemic phenobarbital caused an acute and dose-dependent behavioral and EEGraphic anticonvulsant effect both in WARs. The dose of phenobarbital 15 mg/kg protected animals almost completely, without side effects such as ataxia and sedation. In our data, this endogenous “natural” seizure blockade (or termination) seems to be similar to the “forced” seizure abolition, like the one caused by a systemic non-ataxic phenobarbital dose, because in both cases an intense decrease in the EEG main frequency oscillation can be seen in SNPr and SC. Intranigral phenobarbital or muscimol did not protect animals, and actually induced an increase in the main EEG frequency oscillation in SC.
The main finding of the present study is that, in contrast to what is well believed about the incapacity to control audiogenic seizures by the striato-nigro-tectal circuitry, we collected here evidences that these nuclei are involved in the ability to block these seizures. However, the striato-nigro-tectal circuitry in WARs, a genetically developed strain, seems to have different functional mechanisms when compared with normal rats.