Mice were placed in the center of the maze facing an open arm and their behaviors videotaped and recorded for 5 min. SR141716 (SR) dose (0.3, 1.0 or 3.0 mg/kg, i.p.)-dependently decreased % open arm entries (A), % open arm time (B) and open arm time (sec) (C), and thereby suppressed the open arm exploration of the EPM, in mice repeatedly treated with THC (10 mg/kg, s.c.) rather than vehicle. Veh/veh n=15, THC/veh n=10, veh/SR0.3 n=10, THC/SR0.3 n=10, veh/SR1.0 n=10, THC/SR1.0 n=10, veh/SR3.0 n=15, THC/SR3.0 n=15. Data represent mean ± SEM, which were analyzed by two-way ANOVA with Bonferroni post-hoc tests. The significance is denoted by ** p < 0.01 and *** p < 0.001 vs mice repeatedly treated with vehicle and then challenged with SR141716 at a dose of 3.0 mg/kg, by # p < 0.05 and ### p < 0.001 vs mice repeatedly treated with THC and then challenged with SR141716 at a dose of 0.3 mg/kg, and by ˆˆ p < 0.01 and ˆˆˆ p < 0.001 vs mice repeatedly treated THC and then challenged with vehicle.