(a) Timeline for CPP conditioning, acquisition, post-abstinence, extinction, and stress-induced reinstatement. Arrows indicate test days for which data are represented in (b) and (c) for male and female mice, respectively. Significant stress-induced reinstatement of nicotine CPP is seen for male mice trained with 0.5 mg/kg nicotine and for female mice trained with 0.5 mg/kg and 0.75 mg/kg nicotine. *p < 0.05 compared to pretest day within nicotine dose using Dunnett’s tests.