Figure 3.

A. Behavioral sensitization in Nac1 mutant and wild-type mice. No significant differences between the wild type and mutant mice during the habituation period (days 1−3; saline injections only). A geneotype effect is present on the first day of cocaine administration (day 4). During the development of sensitization (days 5−10) cocaine-treated (10mg/kg i.p. injection) wild-type mice and Nac1 mutant mice exhibit significantly more ambulatory activity than saline-treated mice Both cocaine-treated groups exhibit sensitization on the challenge days (days 29 and 40; 5mg/kg cocaine). # p < 0.05 from corresponding saline group on same day, and * p < 0.05 from corresponding group on day 4 (n = 6 per group). (ANOVA; Fisher's PLSD post hoc test). B. Behavioral sensitization to amphetamine (2 mg/kg) in Nac1 mutant mice (NAC1^−/−) and wild-type mice. No significant differences appear between geneotypes during the habituation period (days 1−3; saline injections only). During the development of sensitization (days 4−7) amphetamine-treated mice exhibit significantly more ambulatory activity than saline-treated mice in all cases except for Nac1 mutant mice on the first and second days of development (days 4 and 5). Both groups show no difference in ambulation in response to saline after development of sensitization (day 90) and both amphetamine-treated groups exhibit sensitization on the challenge days (day 91; 2mg/kg amphetamine). # p < 0.05 from corresponding saline group on same day, * p < 0.05 and + p < 0.01 from corresponding group on day 90 (n = 6 per group). (ANOVA; Fisher's PLSD post hoc test).