Measurement of acute and chronic behavioural effects of methamphetamine in the mouse

A simple and reliable method was developed for rating the dose-related behavioural effects of methamphetamine in male Swiss Albino mice for acute or chronic drug treatment. This procedure was based on a frequency count of certain behaviours made at 15-min intervals over a 90-min period following drug administration. The Fisher Randomization procedure was adapted to analyze behavioural data for the chronic studies. Clear-cut, dose-related behavioural responses occurred following acute (+)-methamphetamine administration and ranged from decreased quiescence (0.64 mg/kg) through increased locomotor activity (2.5 mg/kg), a mixture of stereotyped behaviour and increased locomotor activity (5.0 and 7.5 mg/kg), to primarily stereotyped gnawing, licking or sniffing (10 mg/kg). In studies involving chronic administration of (+)-methamphetamine at 0.64, 2.5 and 10 mg/kg conducted over six and seven weeks, behavioural responses were more exaggerated than in acute studies. All behaviours returned to normal levels in the recovery week except for locomotor activity at the 10 mg/kg dosage. In some animals, chronic treatment with 10 mg/kg (+)-methamphetamine led to protracted self-tearing that replaced the gnawing, licking, sniffing stereotype.