Fig. 1

Effects of exposure to different doses of methamphetamine (METH) place preference on the pretest and reinstatement day in rats. There were no significant differences in conditioning scores between any METH groups with control group on the pretest (a; n = 8 in each group). On the reinstatement day, the preference score of 10 mg/kg METH vs 5 mg/kg METH group was significant (^♠♠♠P < 0.001). The preference scores of METH 5 and 10 mg/kg vs the other groups were significant (^***P < 0.001 and ^*P < 0.05, respectively; a). Moreover, a comparison of pretest and reinstatement days in METH 5 and 10 mg/kg showed significant differences (^&&&P < 0.001). Also, different doses of METH did not alter the locomotor activity in comparison with the control group (n = 8 in each group; b)