Effects of CAB2-015 or BAK4-54 on basal or oxycodone-enhanced locomotor activity. A: Pretreatment with CAB2-015 (4-10 mg/kg, i.p., 15 min prior to oxycodone injection) dose-dependently inhibited oxycodone-enhanced locomotion. B: Pretreatment with BAK4-54 (4-10 mg/kg, i.p., 15 min prior to oxycodone injection) dose-dependently inhibited oxycodone-enhanced locomotion. C/D: CAB02-15 or BAK4-54 alone, at the same doses, had no effect on basal locomotor activity. *p<0.05, **p<0.01, compared to the vehicle group. N=8 in each group.