Anti-nociceptive Activity of Quebracho tannin Extract on Pain Induced by Formalin and Writhing Tests in Mice

Background: Based on positive role of the tannins for pain relief, there is no report for possible antinociceptive activity of the Quebracho tannin. Objectives: This study aimed to determine the anti-nociceptive activity of the Quebracho tannin extract (QTE) on pain in mice. Materials and Methods: For this purpose, ۳۴۰ mice were used for formalin and writhing tests each including ۴ experiments with ۴ sub-groups. In experiment ۱, mice were injected with saline, QTE (۱۰۰ mg/kg), QTE (۲۰۰ mg/kg), QTE (۴۰۰ mg/kg), and morphine (۵ mg/kg). In the second experiment, injections included saline, QTE (۴۰۰ mg/kg), naloxone (۲ mg/kg), and QTE + naloxone. Experiments ۳ and ۴ were similar to experiment ۲, except that mice injected were with NG-nitro arginine methyl ester (L-NAME, ۱۰ mg/kg) and cyproheptadine (۴ mg/kg) instead of naloxone. Then, formalin (۱%) was injected, and time spent for licking the injected paw was recorded until ۳۰ minutes following injection in the first and second phases. Finally, injections in ۴ experiment groups were the same, and animals were intraperitoneally injected with acetic acid, and contractions were recorded in the writhing test category. Results: According to the results, QTE (۱۰۰, ۲۰۰, and ۴۰۰ mg/kg) decreased pain in the injected paw (P = ۰.۰۰۱) and inhibited the pain response by ۵۹.۳۷% (P = ۰.۰۰۱). Moreover, the injection of naloxone + QTE significantly decreased pain in the injected paw (P = ۰.۰۲۱). Eventually, the injection of the L-NAME + QTE significantly reduced the anti-nociception effect of the QTE on the formalin test (P = ۰.۰۳۱) and writhing contractions (۵۵.۷۵%, P = ۰.۰۳۳). Conclusion: These findings suggested anti-nociceptive properties of the QTE mediated by opioidergic and nitrergic systems.

Keywords:

Quebracho tannin , Pain , Formalin test , Mice