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. Author manuscript; available in PMC: 2013 Feb 1.
Published in final edited form as: Biol Psychiatry. 2011 Aug 27;71(3):184–191. doi: 10.1016/j.biopsych.2011.07.024

Figure 2.

Figure 2

Effect of nicotine withdrawal on basal DA levels and nicotine-induced DA signals measured by microdialysis in the NAc. (A) The chronological order of nicotine treatment, nicotine withdrawal, and the experiments. (B) Dialysate DA concentrations at baseline and after an i.p. injection of saline and nicotine (1 mg/kg) following 1 day of withdrawal from 4 or 12 weeks (wk) of chronic nicotine treatment (n = 7–9). ANOVA revealed a group effect in both cases: control vs. 4-week, F(1, 14) = 6.35, p < 0.05; control vs. 12-week, F(1, 14) = 8.56, p < 0.05. A control injection of saline (i.p.) did not significantly alter baseline DA levels between the groups: F(2, 20) = 1.10, p > 0.05. (C) Nicotine withdrawal decreased basal DA levels compared to the control. * p < 0.05, one-way ANOVA. (D) The peak DA response to a nicotine challenge (1mg/kg, i.p.) was not different between the groups. (E) Normalization of the dialysate DA signals revealed that the response to nicotine was enhanced in both withdrawal groups compared to the control (n = 7–9), as assessed by a two-way ANOVA. 4-week vs. control, F(5, 65) = 3.39, p < 0.05*; 12-week vs. control, F(5, 70) = 3.21, p < 0.05*. (F) The peak nicotine-induced DA response (% of basal) was higher in both withdrawal groups than in the control. * p < 0.05 by t-test.