Figure 4.

Effects of microinjection of the D₂ receptor antagonist sulpiride (100 µM, n = 8) or the D₁ receptor antagonist SCH23390 (100 µM, n = 6) into the nucleus accumbens core 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-infusions of 200 mg% ethanol in the posterior ventral tegmental area in all sessions; the microinjection of sulpiride (panel A) or SCH-23390 (panel B) 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).