Figure 5.

The effects of administration of (A) 12% DMSO as a vehicle and different doses of sulpiride as selective D2-like receptor antagonist, (B) 0.25μg (C) 1μg and (D) 4μg per 0.5μl DMSO into the dentate gyrus (DG), 5 min before injection of priming dose of morphine (1 mg/kg;sc) in reinstatement day (24h after the last extinction day) decreased the conditioning score as compared to that in post-test day. Each column represents the mean ±SEM of 5–6 rats.

**P<0.01 and ***P<0.001 compared with pre-test day

†††P<0.001 compared with post-test day

+P<0.05 and +++P<0.001 compared with the last day of extinction period