All data are displayed as the means ± SEM unless otherwise noted. Animal behavioral data were analyzed using one- or two-way analysis of variance with post-hoc Tukey testing or, for CPP data with t-testing. The outcome measures of interest between the placebo-treated and ondansetron-treated groups were compared using paired t-test and the Wilcoxon's signed-rank test where appropriate. Normal distribution was determined using QQ plots and the Kolmogorov–Smirnov test. Analyses were performed with SAS 9.1 statistical package (Cary, Illinois, USA) with P value of less than 0.05 considered statistically significant.
