Anti-nociceptive and anti-inflammatory effects of cyanocobalamin (vitamin B12) against acute and chronic pain and inflammation in mice.

In this study, the anti-nociceptive and anti-inflammatory effects of cyanocobalamin (Vit B12) against acute and chronic pain and inflammation were evaluated in mice. Vit B12 (0.87, 1 and 1.77 mg/kg) were injected intraperitoneally. The anti-nociceptive effects against acute pain were examined using hot-plate and writhing tests. The chronic pain was examined 14 days after sciatic nerve ligation using the hot-plate test. Morphine (10 mg/kg) was used as a positive control. Anti-inflammatory effects of Vit B12 against acute and chronic inflammation were assessed using xylene-induced edema in ears and granuloma caused by compressed cotton implantation, respectively. In these tests, sodium diclofenac (15 mg/kg) was used as a positive control. Vit B12 showed a dose related effect in acute anti-nociceptive test and increased the anti-nociceptive effect of morphine in chronic treatment. Vit B12 demonstrated an anti-nociceptive effect in chronic studies as single or continues daily treatment and increased significantly the anti-nociceptive effect of morphine. All doses of Vit B12 significantly decreased xylene-induced ear edema. Maximum anti-inflammatory effect (37.5%) was obtained at dose of 1 mg/kg. In chronic inflammation, Vit B12 significantly decreased granuloma formation in mice. In conclusion our work presents some experimental evidence supporting the administration of cyanocobalamin in controlling acute and chronic neuropathic pain. Cyanocobalamin may have anti-inflammatory effect. It may reduce tolerance to anti-nociceptive effect of morphine as well.