Antinociceptive Effect of Vaccinium Myrtillus in Diabetic Rats

Diabetes mellitus in long-term accompanies with inappropriate complications like retinopathy and neuropathy and increased pain sensation due to neuropathy. Since there is some evidence on protective and antidiabetic effects of Vaccinium myrtillus (VM), this study was designed to investigate the antinociceptive effect of Vaccinium myrtillus (VM) in streptozotocin-diabetic rats using formalin test and hot tail immersion tests. In this experimental study, male rats were divided into equal-sized control, VM-treated control, diabetic, sodium salicylate (SS)-treated diabetic, and VM-treated diabetic groups. For induction of diabetes, streptozotocin at a dose of 60 mg/kg (i.p) was injected. The treatment groups received oral administration of VM-mixed pelleted food (5%) for 6 weeks with no limitation. Finally, hyperalgesia were assessed using standard formalin and hot tail immersion tests. VM treatment of diabetic rats reduced pain score in chronic phase up to 17.9% (p<0.05). Meanwhile, SS administration significantly reduced pain score at chronic phase of the test up to 23.6% (p<0.05). Regarding hot tail immersion test, diabetic rats showed a significant 37.4% reduction in tail flick latency as compared to control ones (p<0.05). Although VM treatment of diabetic rats increased this latency relative to untreated diabetics up to 11.3%, but the existing difference was not statistically significant. Six-week administration of VM could attenuate nociceptive score in chronic phase of formalin test in streptozotocin-induced experimental model of diabetes mellitus and has no effect on thermal pain threshold.