Effects of buprenorphine (1mg/kg) and naltrexone (1mg/kg), alone or in combination, in the mouse elevated plus maze (A,B,C) and light-dark box (D,E,F). The benzodiazepine diazepam (2 mg/kg) was included as a positive control. The time spent in the open arms (A), number of entries into the open arms (B) and total ambulation (C) in the elevated plus maze are shown (n=10 per group). The time spent in the light box (D), in the dark box (E) and total ambulation (F) in the light dark box are shown (n=18 per group). All values are the mean ± SEM. *p< 0.05 compared to saline.