Figure 3. Conditioned Place-Preference of Group 3 Mice.
Mean ± SEM of CPP scores. Group 3 mice have a roughly 1:1 ratio of 129 and C57 strain backgrounds, via outcrossing the C57-congenic group 2 mice to 129S1/SvImJ mice. (a) Group 3 wild-type control mice (cocaine: n = 16, saline: n = 8) show an apparently large trend toward CPP induced by 20 mg/kg cocaine (p = 0.070), but this result is not statistically significant due to larger variations than in the inbred mice. (b) 129B6 DAT-CI littermates (cocaine: n = 8, saline: n = 8) show a robust CPA induced by 20 mg/kg cocaine in contrast to group 2 DAT-CI mice (a priori contrast, denoted by ‡; p < 0.05). All other statistics are comparisons of the time bias (CPP score) observed post-conditioning (open bars) relative to saline-conditioned control mice (*, p < 0.05; **, p < 0.01).