Fig. 7. Anti-interleukin (IL)-10 antibody, SB203580, and heme oxygenase-1 (HO-1) antagonist zinc protoporphyrin reverse the suppressive effect of amitriptyline on proinflammatory cytokine production. Protein levels for tumor necrosis factor-α (TNFα), IL-1β, and IL-6 were measured in the different groups (n = 4 of each group). CONT = saline infusion; MO = morphine infusion; MO+AMI = morphine plus amitriptyline coinfusion; MO+AMI/Anti-IL- 10Ab = morphine plus amitriptyline coinfusion plus anti-IL-10 antibody injection for 5 days; MO+AMI+SB = morphine plus amitriptyline plus SB203580 coinfusion; MO+AMI/ZnPP = morphine plus amitriptyline coinfusion plus zinc protoporphyrin injection for 5 days. *** P < 0.001 compared with saline-infused group; ### P < 0.001 compared with morphine-infused group; $$ P < 0.01 compared with saline-, morphine-, and amitriptyline/morphine-infused group.