The role of nitric oxide in antinociceptive activity of pyridoxine

In this study, the role of endogenous nitric oxide in antinociceptive activity of pyridoxine has been investigated by p-benzoquinone (p-BQ) induced writing algesia model in mice. The effects of pyridoxine (0.43 mg/kg), morphine (0.13 mg/kg), L-Arginine (0.32, 5, 50 mg/kg), L-NAME (75 mg/kg) and methylene blue (MB 5 and 40 mg/kg) in the abdominal constriction of mice induced by p-BQ were evaluated by s.c. single and co-administrations. As a result pyridoxine, morphine, L-Arginine, L-Name, and Methylene Blue were induced antinociception where as L-Arginine and Methylene Blue possesed hyperalgesia at dose levels 10-40 and 40 mg/kg respectively. L-Arginine and Methylyne Blue indicates a dual effect in nociceptive processes whereas hyperalgesic activities of both compounds were totally abolished when combined with 0.43 mg/kg pyridoxine. As pyridoxine is an activator of guanyl cyclase and evident c-GMP, The abovementioned results are that L-Arginine/NO-c-GMP pathway involves the antinociceptive effect of the compound.