SA4503 attenuates and enhances methamphetamine-induced hyperactivity. Mice were placed in an activity monitor for 45 min, injected (i.p.) with SA4503 (1 – 31.6 µmol/kg) or saline, returned to the monitor for 15 min, injected (i.p.) with methamphetamine (0.5 mg/kg) or saline, and placed in the monitor for 60 min. Panel A depicts distance traveled (in cm) summed across the 60-min period after methamphetamine or saline injection. The asterisk designates a significant (p < 0.05, Tukey post-hoc analysis) difference from the group administered saline and methamphetamine. Panels B, C and D depict distance traveled (in cm) in 5-min intervals. The left arrow designates SA4503 or saline injection and the right arrow designates methamphetamine or saline injection. Asterisks designate a significant (p < 0.05, Tukey post-hoc analysis) difference from the group administered saline and methamphetamine at the respective time point.