Figure 1

Locomotor sensitization by repeated caffeine and SCH58261 administration in habituated C57BL/6 mice. Caffeine (10 mg/kg/day, i.p.), SCH58261 (2 mg/kg/day, i.p.) or vehicles were administered continuously for 10 days except with one washout on day 6. Three days after the last injection of Caffeine, SCH58261 or vehicles, mice were challenged with caffeine (10 mg/kg, i.p.) or SCH58261 (2 mg/kg/day, i.p.) respectively. The horizontal locomotor activity was measured for 30 min. Data represent means ± SEM (n = 4-6). a, d The time course of locomotor activity measured over 10-min intervals. a caffeine-treated group compared to saline-treated group(P < 0.001) and d SCH58261-treated group compared to DMSO-treated group (P = 0.003, by two-way ANOVA); b, e Total locomotor activity counts during the 30-min period following acute administration of caffeine or SCH58261. b caffeine-treated group compared to saline-treated group (P < 0.01)and e SCH58261-treated group compared to DMSO-treated group (P < 0.05); c, f Total locomotor activity counts during the 30-min period following acute administration of caffeine in caffeine- treated group and acute administration of SCH58261 in SCH58261-treated group on day1, day7 and day15. c locomotor activity of caffeine-treated group on day7 and on day15 compared to locomotor activity of caffeine-treated group on day1, and f locomotor activity of SCH58261-treated group on day7 and on day15 compared to locomotor activity of SCH58261-treated group on day1 respectively (*P < 0.05 and **P < 0.01 by Student's test).