Figure 3

Locomotion in PTPRD homozygous knockouts, heterozygous knockout and wild-type mice in different settings. Values are mean ± SEM of the number of meters traveled. (A) During the first pretest, mice were exposed for the first time to the CPP apparatus and allowed to explore both sides (n = 31–51/genotype). (B) During the second pretest, mice were placed in the CPP apparatus and allowed to explore both sides (n = 31–51/genotype). (C) During the first exposure to cocaine, were confined to one side of the CPP apparatus and experienced effects of the cocaine doses shown (n = 10–16/genotype/dose for wild-type and heterozygotes, n = 4–5 for homozygotes). (D) Ratios between locomotion during first versus second exposures to differing cocaine doses (locomotor sensitization) in mice with PTPRD genotypes shown. Reduced PTPRD expression provided significantly different locomotor sensitization (repeated-measures ANOVA genotype × session × dose, p = 0.048). Scheffé post hoc testing revealed that differences between wild-type and homozygous knockouts were highly significant (p < 0.001), whereas heterozygotes were essentially indistinguishable from the wild-type mice (p = 0.988). n = 11–12 mice of each genotype for each dose. Gender displayed no significant main effect, interaction with genotype or interaction with dose (ANOVA, p = 0.334, 0.495 and 0.521, respectively). (E) During habituation after being placed into a larger, novel apparatus. Points represent mean ± SEM for meters traveled during each 10-min epoch of the 60 min after first exposure to a novel apparatus. n = 15–16 mice of each genotype. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001.