Figure 9.
Morphine failed to induce hyperalgesia in CaMKIIαT286A mutant mice. Male CaMKIIαT286A mutant and littermate wild-type mice were subcutaneously administered saline or morphine sulfate (day 1–3: 20 mg/kg/d; day 4: 40 mg/kg, twice daily). Baseline pain thresholds were not significantly different between wild-type and mutant mice. Mechanical and thermal sensitivities were tested on day 5. Morphine treatment successfully induced hyperalgesia in CaMKIIαT286A+/+ mice (**p < 0.01, compared with the baseline). However, CaMKIIαT286A−/− mice failed to develop OIH (p > 0.05, compared with the baseline). Data are expressed as mean ± SEM; n = 6 for each group.