Figure 7.

Inflammatory pain impacts motivated behavior. A, Schematic of the experimental design is shown for the training and PR sessions for heroin and sucrose self-administration. Number of responses on the active lever (circle) versus the inactive lever (square) under FR1, FR2, and FR5 schedules of reinforcement with 50 μg/kg/infusion heroin (B) or sucrose pellets (C) as the reinforcer (data are mean ± SEM). Effect of inflammatory pain on the PR step number (% from baseline) 48 h after saline (black represents baseline; gray represents after injection) or CFA injection (red represents baseline; pink represents after injection) with heroin 50 μg/kg/infusion (D), 200 μg/kg/infusion (E), or sucrose pellets (F) as the reinforcer. *p < 0.05 versus baseline (two-way ANOVA with repeated measures followed by Bonferroni corrections for multiple comparisons). n = 10 per group.