Figure 1

a Rat weight during the course of the self-admin study. Methamphetamine self-administration rats (n = 11) gained less weight than controls (n = 11) for the duration of the study; the weights were significantly different at day 35 and day 40 (p < 0.05, Student’s t-test). b Number of active and inactive lever responses over the course of the study for methamphetamine self-administration rats, and c control rats lever responses.