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 t he incidence, intensity, and duration of electroconvulsion were invest igated 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 me thamphetamine (3 mg/kg) reduced the incidence of the electroconvulsion in mice; however, the duration of each phase of the convulsion was pr olonged by acute methamphetamine. Repeated administration of methamphe tamine prolonged the duration of clonic phase of the convulsion and en hanced the acute methamphetamine-induced reduction in the incidence of electroconvulsion. These data indicate that the incidence of electroc onvulsion is regulated by different mechanisms underlying the duration and intensity of the convulsion.