Fig. 1.

Effects of mecamylamine-precipitated nicotine withdrawal on extracellular levels of CRF-L-IR in the central nucleus of the amygdala and CRF antagonist blockade of precipitated withdrawal-induced anxiety-like behavior in rats by using the defensive burying test. (A) Effect of mecamylamine (1.5 mg/kg, i.p.) -precipitated withdrawal on extracellular levels of CRF-L-IR in the central nucleus of the amygdala as measured by in vivo microdialysis in chronic nicotine pump-treated (nicotine-dependent, n = 7) and chronic saline pump-treated (nondependent, n = 6) rats (*, P < 0.05 vs. nondependent). (B) CRF-L-IR levels expressed as percentage of baseline (first three samples) during the first four samples after vehicle or mecamylamine injections (*, P < 0.05 vs. vehicle). (C) CRF₁ antagonist blockade of precipitated withdrawal-induced anxiety-like behavior in rats by using the defensive burying test. Mecamylamine (1.5 mg/kg, i.p.) injection in nicotine-dependent rats increased the time spent burying (*, P < 0.05 vs. vehicle), an effect blocked by pretreatment with the CRF₁ antagonist (MPZP, 4 mg/kg s.c., −1 h) (n = 7–9 per group, #, P < 0.05 vs. mecamylamine). Data represent mean ± SEM.