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. Author manuscript; available in PMC: 2007 Jun 21.
Published in final edited form as: Psychopharmacology (Berl). 2001 Sep 11;159(1):2–9. doi: 10.1007/s002130100901

Figure 3.

Figure 3

Effect of repeated administration of d-amphetamine on the locomotor response of DAT+/+, DAT+/−, and DAT−/− mice. Animals were first exposed to the testing environment without any injection (preexposure phase, not shown), followed by a daily injection of d-amphetamine (1 mg/kg, s.c.; filled symbols) or saline (open symbols) in the same environment for eight days (pairing phase). During the saline test (day 9), all mice were exposed in a drug-free state to the environment repeatedly associated to the effect of d-amphetamine or saline. During the drug test (day 10), all mice were injected with d-amphetamine (0.5 mg/kg, s.c.) to examine the pharmacological sensitization to the behavioral effects of the drug. Locomotion was evaluated daily during a 1 h session and is expressed as total number of photocell beam breaks. Please note that DAT−/− mice are hyperactive when compared to DAT+/+ and DAT+/− mice and that the vertical scales in the three graphs are different. Values represent mean ± SEM; DAT+/+, n = 6–9; DAT+/−, n = 6–8; and DAT−/−, n = 6–8. ANOVA followed by Tukey’s test: * p<0.05 and ** p<0.01, vs. saline-treated mice of the same genotype at the same time point; # p<0.05, vs. the first pairing day within the same treatment group; § p<0.05 and §§ p<0.001, vs. the last pairing day within the same treatment group.