Figure 2.

Daily N-acetylcysteine prevents cocaine-induced behavioral sensitization without altering acute locomotor activity. a–c, Total distance traveled (mean centimeters ± SEM) is depicted in 10 min intervals (a, b) or summed across the 2 h session (c). Group designations refer only to treatments on days 1–7, at which time rats received saline or N-acetylcysteine (0 or 60 mg/kg, i.p.) before each of seven daily injections of saline or cocaine (15 mg/kg, i.p., on days 1 and 7; 30 mg/kg, i.p., on days 2–6). These drug assignments resulted in four groups: Sal–Sal (N = 11), NAC–Sal (N = 11), Sal–Coc (N = 13), and NAC–Coc (N = 15). After a 21 d drug-free period, locomotor activity was measured on day 28 of the experiment after a saline or cocaine (15 mg/kg, i.p.) challenge in the absence of N-acetylcysteine pretreatment. The arrow indicates the timing of the saline or cocaine injection administered on day 1 (a, c), day 7 (c), or day 28 (b, c) of the experiment. a, *Significant difference from interval immediately preceding the saline or cocaine injection regardless of N-acetylcysteine treatment; Dunnett's t, p < 0.05. ^#Significant difference from rats injected with saline (0 cocaine) regardless of N-acetylcysteine treatment; ANOVA, p < 0.05. b, *Significant difference from the interval immediately preceding the saline or cocaine injection; Dunnett's t, p < 0.05. ^#Significant difference from every other group; Dunnett's t, p < 0.05. c, *Significant difference from day 1; Dunnett's t, p < 0.05. ^#Significant difference from every other group; Dunnett's t, p < 0.05.