Figure 2.

Effects of microinjection of vehicle (A, n = 8) or the D₂ receptor antagonist sulpiride (B & C, 10 and 100 µM, n = 7 and 10 respectively) into the nucleus accumbens shell on responses (Mean ± SEM) on the active and inactive lever for self-infusions of 200 mg% ethanol into the posterior ventral tegmental area. All rats received self-infusion of 200 mg% ethanol into the posterior ventral tegmental area in all sessions; the microinjection of sulpiride was given immediately prior to sessions 5 and 6. * Responses on the active lever were significantly higher than responses on the inactive lever (p < 0.05). # Responses on the active lever were significantly lower than average basal responses during sessions 3 and 4 (p < 0.05). Response on the active lever in 30-min bins during acquisition session 4 and following treatment with 100 µM sulpiride in session 5 (panel D).