Ameliorative Potential of Morin in Streptozotocin-Induced Neuropathic Pain in Rats
Purpose: To investigate the protective effect of morin, a naturally occurring bioflavonoid of Moraceae family, in experimentally-induced diabetic neuropathy (DN) in rats.
Methods: Diabetes was induced by a single injection (65 mg/kg, ip) of streptozotocin (STZ). Morin (15 and 30 mg/kg/day) oral treatment was started 3 weeks after diabetes induction and continued for 5 consecutive weeks. Pain threshold behavior tests were performed at the end of the treatment. In sciatic nerve, inflammatory cytokines (TNF-á, IL-1â, IL-6), nerve growth factor (NGF) and insulin growth factor (IGF-1) were determined using ELISA kits, while thiobarbituric acid reactive substances (TBARS),
glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) levels were assessed.
Results: Diabetic animals showed apparent decreased paw-withdrawal (39 %, p < 0.05) and tail-flick (31 %, p < 0.05) latency as compared with control group. All the measured biomarkers were altered (p < 0.05 to 0.001) in diabetic rats compared with control non-diabetic animals. Morin treatment attenuated hyperalgesia and analgesia (p < 0.05) respectively. Morin treatment of diabetic rats at both doses significantly decreased the levels of cytokines (p < 0.01), glucose (p < 0.01) and TBARS (p < 0.001), but increased NGF (p < 0.01), IGF-1 (p < 0.01) and GSH (p < 0.01) levels in sciatic nerves compared to untreated diabetic animals. Inhibited activities (U/mg protein) of SOD (1.08 ± 0.16) and CAT (2.77 ± 0.36) in sciatic nerve of diabetic rats also found corrections (2.09 ± 0.11, p < 0.01) and (4.53 ± 0.57, p < 0.01) after morin (30 mg/kg/day) treatment, compared with untreated diabetic animals.
Conclusion: These findings demonstrate the protective effect of morin mediated through reduction of oxidative stress and inflammatory process, and suggest the therapeutic potential of morin in the attenuation of diabetic neuropathy.
Keywords: Morin, Diabetes, Neuropathy pain, Oxidative stress, Anti-inflammatory