Changes in METH intake and body weight over the course of self-administration in rats.

<p>(A) Escalation of METH intake in rats. Symbols indicate average daily amount of actively self-administered METH during each of 8 consecutive daily sessions (means ± SEM; n = 11). Rats increased METH intake on days 3–8 compared with days 1 and 2, and days 7–8 showed further increases in intake compared with day 3. Data analyzed by one-way ANOVA for repeated measures, followed by Tukey's multiple comparison test: *** <i>p</i><0.001 in comparison with sessions 1 and 2, # <i>p</i><0.05 in comparison with session 3. (B) METH caused significant decreases in body weight in the animals that actively self-administered the drug (means ± SEM; n = 9). Data analyzed by two-way ANOVA for repeated measures, followed by Tukey's multiple comparison test: * <i>p</i><0.05; *** <i>p</i><0.001 in comparison to saline group.