Antinociceptive activity of Tribulus terrestris oral feeding in diabetic rats: Involvement of lipid peroxidation

Background and Objective: Due to the presence of some evidence for anti-diabetic and antioxidant activity of Tribulus terrestris (TT), this study was designed to investigate the anti-nociceptive effect of TT in streptozotocin-diabetic rats using formalin test and hot tail immersion tests. Materials and Methods: Rats were divided into control, TT-treated control, diabetic, sodium salicylate (SS)-treated diabetic (as positive control), and TT-treated diabetic groups. The treatment groups received oral administration of TT-mixed pelleted food (3%) for 5 weeks. Serum level of malondialdehyde (MDA) as a reliable marker of lipid peroxidation was also measured. Results: TT treatment of diabetic rats reduced pain score only in chronic phase of the formalin test (p < 0.05). Meanwhile, SS administration significantly reduced pain score only at chronic phase of the 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). Although TT treatment of diabetic rats increased this latency relative to untreated diabetics but the existing difference was not statistically significant. TT treatment of diabetic rats also significantly reduced MDA level versus untreated diabetics (p < 0.01). Conclusion: Taken together, 5-week administration of TT could attenuate nociceptive score in chronic phase of formalin test in streptozotocin-induced experimental model of diabetes mellitus and has no significant effect on thermal pain threshold and part of its beneficial effect is exerted via attenuation of lipid peroxidation and possibly reduction of oxidative stress.