Antinociceptive effect of Terminalia bellirica in diabetic peripheral neuropathy: A comparison with fluoxetin, imipramine and quercetin

The present study was undertaken to evaluate the possible antinociceptive effect of Terminalia bellirica fruit aqueous extract in animal models of diabetic neuropathic pain. Diabetes was induced by streptozotocin (50 mg/kg i.p.). T. bellirica (70 mg/kg), fluoxetine (14.5 mg/kg), imipramine (10.5 mg/kg) and quercetin (10 mg/kg) were administered orally for 21 consecutive days, starting after 4th week in streptozotocin induced diabetic rats. Hot plate test, tail immersion test and formalin test were used to assess the antinociceptive activity. For assessment of the role of opioid receptors in antinociception of T. bellirica, naloxone (2 mg/kg, i.p.) as opioid receptor antagonist was injected prior to its administration. Thiobarbituric acid reactive species (TBARS), catalase and superoxide dismutase were also estimated to evaluate oxidative stress. Diabetes induced axonal degeneration was assessed histopathologically. T. bellirica attenuated hyperalgesia in streptozotocin induced diabetic rats. Furthermore, T. bellirica significantly decreased TBARS and restored the activity of SOD and catalase towards normal. Histopathological examination of sciatic nerve also confirms the protective nature of T. bellirica. Antinociceptive activity of T. bellirica was reversed by prior administration of naloxone, and. was comparable with standard treatments like fluoxetine, imipramine and quercetin. The antidepressant and anti-oxidant activity of T. bellirica may be responsible for its antinociceptive action in diabetic neuropathy.