Changes in the incidence and duration of electroconvulsions after acute or subchronic treatment with methamphetamine in mice.

The effects of acute or subchronic treatment with methamphetamine on the incidence, intensity, and duration of electroconvulsion were investigated in mice. The convulsion was induced by electrical stimulation (100 Hz, 60 mA, 0.1-s duration) through electrodes located at each ear of mice, then analyzed by the vibration monitoring apparatus. Acute methamphetamine (3 mg/kg) reduced the incidence of the electroconvulsion in mice; however, the duration of each phase of the convulsion was prolonged by acute methamphetamine. Repeated administration of methamphetamine prolonged the duration of clonic phase of the convulsion and enhanced the acute methamphetamine-induced reduction in the incidence of electroconvulsion. These data indicate that the incidence of electroconvulsion is regulated by different mechanisms underlying the duration and intensity of the convulsion.