Figure 2.

Effects of varenicline on cocaine+nicotine self-administration: each dose of cocaine+nicotine is shown above each set of bar graphs. Ordinate: the number of cocaine+nicotine injections per day for the last three days of the treatment period. Drug self-administration during saline treatment is shown as open bars. Drug self-administration during varenicline treatment is shown as gray bars (0.004 mg/kg/h) and black bars (0.04 mg/kg/h). The top row shows drug self-administration when low minimally reinforcing doses of cocaine+nicotine were available. The bottom row shows drug self-administration when higher reinforcing doses of cocaine+nicotine were available. The ANOVA found a significant effect of varenicline (0.04 mg/kg/h; p=0.025) on self-administration of 0.0032 mg/kg/inj cocaine+0.0032 mg/kg/inj nicotine (F(2,8)=4.936; p=0.04) but not on 0.0032 mg/kg/inj cocaine+0.001 mg/kg/inj nicotine, 0.01 mg/kg/inj cocaine+0.001 mg/kg/inj nicotine, or 0.01 mg/kg/inj cocaine+0.0032 mg/kg/inj nicotine (all Fs<1.08; ps=0.38–0.44). Each data point represents the mean±SEM of 4–5 monkeys. *p<0.05 vs baseline.