Subcutaneous pretreatment of (A) ketoprofen (1, 2, 4 mg/kg), (B) morphine (0.32, 1 3.2 mg/kg), and (C) U50,488H (0.1, 0.32, 1, 3.2, 10 mg/kg) on intraperitoneal 1% acetic acid (AA)-induced conditioned place aversion (CPA). For each panel, the abscissa shows drug dose in mg/kg (log scale, V=vehicle), and the ordinate shows preference score expressed as the time spent in drug-paired side of the box. Vehicle was saline for test drugs and sterile water for AA. “AA” represents time spent acid-induced aversion score (in sec) on test day. Data are expressed as means ± S.E.M. from 6–10 mice. Filled circles points indicate that the AA treatment is significantly different than the V treatment. Filled triangles points indicate significant difference from the V treatment and filled squares points indicate significant difference from the AA treatment by one-way ANOVA followed by Tukey’s post hoc test (p<0.05).