ABSTRACT
Introduction: Hyperalgesia is considered as one of the marked signs of subchronic diabetes mellitus in patients that could affect their lifestyle. This study was designed to investigate the anti-nociceptive effect of chronic administration of quercetin in streptozotocin [STZ]-diabetic rats using formalin and hot tail immersion tests. Methods: Rats were divided into control, control or diabetic groups receiving sodium salicylate, untreated diabetic, and quercetin-treated control and diabetic groups. The treatment groups received i.p. administration of quercetin at a dose of 10 mg/kg for 6 weeks. Finally, hyperalgesia were assessed using standard formalin and hot tail immersion tests. Meanwhile, some markers of oxidative stress were also measured in brain tissue. Results: Quercetin or SS treatment of diabetic rats significantly reduced pain score in chronic phase of formalin test [p<0.05]. Regarding hot tail immersion test, diabetic rats showed a significant reduction in tail flick latency as compared to control ones [p<0.05] and quercetin treatment of diabetic rats did significantly increase this latency relative to untreated diabetics [p<0.05]. Quercetin treatment of diabetic rats also significantly decreased brain level of malondialdehyde [MDA] [p<0.05] and nitrite [p<0.05] and slightly increased activity of superoxide dismutase [SOD] relative to diabetics. Discussion: Taken together, chronic administration of quercetin could attenuate nociceptive score in chronic phase of formalin test in streptozotocin-diabetic rats and could also increase threshold of thermal nociception