Figure 3.
(A) Dose-response curve of antalarmin (0, 5, 10, 20 mg/kg) when systemically (i.p.) injected in Wistar (n = 7), as well as GG (n = 12), and AA (n = 14) msP rats as assessed on operant alcohol self-administration on a fixed ratio 3 (FR-3) schedule of reinforcement. The AA msP rat line shows increased sensitivity to antalarmin treatment compared to the other rat line examined. Data are the mean (±SEM) number of rewards earned in 30 min. **p < 0.01, difference from the vehicle-treated groups (0 mg/kg). (B) I.p. pre-treatment with antalarmin (10 mg/kg) fully blocks the escalation of alcohol self-administration (FR-3) elicited by systemic (i.p.) treatment with yohimbine at the dose of 0.625 mg/kg in all rat lines examined [Wistar (n = 8), as well as GG (n = 10) and AA (n = 15) msP rats]. Results are the mean (±SEM) number of rewards earned in 30 min. ***p < 0.001, difference from the groups receiving both vehicle-treatments of antalarmin and yohimbine (−/−); ###p < 0.001, difference from the groups receiving yohimbine 0.625 mg/kg (±). Wistar: white bars; GG: gray bars; AA: black bars. For detailed statistics, see “Results.”