Anti-Inflammatory Role of Thyroid Hormones on Rat Air Pouch Model of Inflammation

Background: Many studies showed anti-inflammatory potential of thyroid hormones, but no direct report available showing influence of thyroid hormones on inflammation state. Therefore, in present study anti-inflammatory and antioxidative role of thyroid hormones being evaluated on rat air pouch model of inflammation. Methods: Reference doses of both the thyroid hormones triiodothyronine (T3) and thyroxine (T4) were administered to rat airpouches. Air pouch model was developed by injecting air into intra-scapular region of animals, followed by carrageenan administration (AP+C). Control animals injected only with air (AP). Results: In AP+C, group an increase was observed in exudate levels of TNF-α, total leukocytes, polymophonuclear cells and mononuclear cells. An increase was also observed in exudates and tissue lipid peroxidation, nitrite and reduced glutathione. These changes were reverted back by the administration of indomethacin (I) or T3or T4. However, effect was more pronounced in case of T3, as compared to other groups on most of the studied parameters. Histopathological changes were also observed in AP+C group, as compared to AP alone and these alterations were also normalized by the administration of I or T3 or T4. In silico interaction of both the thyroid hormones with cyclooxygenase (COX-2) was studied and compared with standard drugs indomethacin and celecoxib. Conclusion: We conclude thyroid hormones have anti-inflammatory potential i.e. mainly mediated through their structural similarity with anti-inflammatory drugs.