Effects of restraint on electroencephalographic variables and monomethylhydrazine-induced seizures in the cat.

The toxic derivative of hydrazine, monomethylhydrazine, at a dosage of 10 mg/kg is a potent convulsant, producing tonic-clonic seizures in the cat. In this study the effects of enforced restraint on susceptibility to MMH-induced seizures was examined in naive animals and in cats prepared neurosurgically with indwelling polygraphic recording electrodes. Using a counterbalanced design, latency to seizure following the intraperitoneal administration of the drug (10 mg/kg) was measured twice in all animals, under restraint and in freely moving conditions. Susceptibility to seizures was significantly decreased under the condition of restraint. Additionally, polygraphic recordings showed that restraint was accompanied by an increased incidence of “synchronous” EEG patterns. These results were not explained by metabolic variables, duration of intertrial interval, or changes in weight. The relationship between observed polygraphic patterns and seizure response is discussed in terms of the physiological alterations attendant upon restraint.