Fig. 1

Effect of l-THP on nicotine SA and comparison to varenicline and bupropion. l-THP decreased nicotine SA in animals trained to stably respond for nicotine infusions. Each pretreatment was tested for three consecutive days all data is presented as mean + S.E.M. a Infusions per session over five days of training (Nic Baseline) and three days of treatment (Test Avg) respectively. Saline demonstrated no effect on nicotine SA, while l-THP at 5 mg/kg displayed a significant effect on nicotine responding. ***p < 0.001, t-test between test avg and nic baseline, n = 6 per group, 3 mg/kg l-THP group n = 12. b Infusions per session averaged in the same manner as the previous panel. l-THP, varenicline, and bupropion significantly reduced nicotine responding compared to respective nicotine baselines, two-way ANOVA **p < 0.01, ***p < 0.001. + denotes comparison of test averages to 5 mg/kg l-THP; the test average of 5 mg/kg l-THP was significantly lower than that of varenicline and saline, +p < 0.05, +++p < 0.001, n = 6 per group. All groups rebounded to baseline responding for nicotine in post test sessions. c Session breakdown of pretreatment across three day repeated testing of nicotine SA. 5 mg/kg l-THP and 1 mg/kg varenicline performed stably across the three day test period while 40 mg/kg bupropion did not, two-way ANOVA with Bonferroni post hoc analysis, all treatment groups were compared to saline treatment, *p < 0.05, **p < 0.01, ***p < 0.001