Fig. 3
The long-term therapeutic effect of U50 on cue-induced reinstatement depends on operant, not contextual, extinction on extinction day 1. Using the same experimental design as previous experiments, a single dose of U50 (5 mg/kg, i.p.) was administered 30 min prior to the first extinction session. The U50 group (n = 7) had access to levers as usual, but the U50 No Lever (U50-NL; n = 7) group did not. U50-NL significantly differed from U50 on the first extinction session with access to levers. Prior treatment with U50, only when levers were present, resulted in a long-lasting therapeutic reduction in cocaine seeking on the cue-induced reinstatement test (**p < 0.01 active lever, ++p < 0.01 inactive lever, comparing U50 to U50-NL)
