THEMED ISSUE: CANNABINOIDS RESEARCH PAPER Spinal and peripheral analgesic effects of the CB2 cannabinoid receptor agonist AM1241 in two models of bone cancer-induced pain

Background and purpose: The activation of CB2 receptors induces analgesia in experimental models of chronic pain. The present experiments were designed to study whether the activation of peripheral or spinal CB2 receptors relieves thermal hyperalgesia and mechanical allodynia in two models of bone cancer pain. Experimental approach: NCTC 2472 osteosarcoma or B16-F10 melanoma cells were intratibially inoculated to C3H/He and C57BL/6 mice. Thermal hyperalgesia was assessed by the unilateral hot plate test and mechanical allodynia by the von Frey test. AM1241 (CB2 receptor agonist), AM251 (CB1 receptor antagonist), SR144528 (CB2 receptor antagonist) and naloxone were used. CB2 receptor expression was measured by Western blot. Key results: AM1241 (0.3–10 mg·kg