LONG-CONTINUOUS OBSERVATION OF THE EFFECTS OF METHAMPHETAMINE ON WHEEL-RUNNING AND DRINKING IN MICE

1. Effects of methamphetamine (MAP) on wheel-running and drinking in m ice, housed under 12-hr light-dark schedule (light period; 06:00-18:00 ), were investigated through long-continuous observation. 2. 2. MAP (1 , 2 and 4 mg/kg, s.c.) acutely increased the wheel-running and drinkin g for 2-4 hr in EI dose-dependent manner after the administration at 1 1:00, midpoint of light period. 3. MAP administered at 11:00 sub-acute ly suppressed the spontaneous increment during dark period (18:00-06:0 0) in both the behaviors. 4. Many factors, such as the time-oil-day an d interval of the administration as well as the dose administered, aff ected the behavioral suppression induced by MAP. 5. In addition to the se findings, the wheel-running and drinking during the light period in creased even on the days without MAP administration. 6. These results suggest that MAP have not only acute stimulant and sub-acute depressan t effects, but also long-lasting effects.