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. 2002 Jun 25;99(13):9026–9030. doi: 10.1073/pnas.142039099

Figure 2.

Figure 2

Short-term sensitization in Per mutants. Locomotor responses to acute and repeated saline/cocaine injections in wild-type (wt) mice or mice carrying a mutation in mPer1 or mPer2 genes after a 3-day withdrawal period are shown. (A) Mean locomotor activity ± SEM after acute cocaine and repeated cocaine injections (wt, n = 13–16; Per1 mutant, n = 9–10; and Per2 mutant, n = 14–15). Two-way ANOVA revealed that cocaine sensitization differed significantly for the different genotypes (see text). Further statistical comparisons between acute and repeated treatment showed the following differences for each genotype: wt, P = 0.04; Per1 mutant, P = 0.78; and Per2 mutant, P = 0.002. * indicates a significant difference to acute cocaine P < 0.05; **, P < 0.01. (B) The increase in locomotor activity after repeated cocaine injections was also calculated as percentage difference in activity to acute cocaine injection. The dashed line indicates mean activity after acute cocaine injection. One-way ANOVA revealed a genotype effect [F(2,36) = 9.5, P = 0.005]. * indicates a significant difference to wt mice, P < 0.05.