Figure 1. Effect of melatonin supplementation on nicotine 2-bottle preference drinking in C57 mice.

When C57BL/6J mice have supplemental melatonin, they drink significantly less nicotine than the controls. Panel (A) shows nicotine dose consumed per day. There was a significant main effect of nicotine concentration (F_{3, 132} = 32.00, p < 0.0001), and melatonin supplementation (F_{1, 132} = 9.68, p < 0.005). Panel (B) shows total nicotine intake over the course of the study, where a significant effect of melatonin supplementation (t = 2.335, df = 34, p < 0.05) was observed. Panel (C) shows total fluid intake where there are no differences by melatonin supplementation (F_{1, 132} = 0.12, p = 0.73) or nicotine concentration (F_{3, 132} = 0.30, p = 0.82). Panel (D) shows nicotine preference, which demonstrated main effects of melatonin treatment (F_{1, 132} = 14.45, p < 0.0005) and nicotine concentration (F_{3, 132} = 9.827, p < 0.0001). Data is displayed as mean ± SEM and n=17 control, 19 melatonin supplemented animals. *denotes main effect differences between melatonin and control conditions.