Effects of α-lipoic acid on oxidative stress parameters in experimental hyperthyroidism

Abstract

Aim: To investigate the effects of α-lipoic acid (ALA) on prooxidant-antioxidant balance in liver tissue, as well as liver function tests in experimental hyperthyroidism.Materials and Methods: For the evaluation of prooxidant-antioxidant balance, reactive oxygen species (ROS), malondialdehyde (MDA), protein carbonyl (PC), ferric reducing antioxidant power (FRAP), glutathione (GSH) levels, and superoxide dismutase, catalase and glutathione peroxidase activities were determined. Histopathological examinations were also performed. Hyperthyroidism was induced by the administration of L-thyroxine [T4, 12 mg/L] in drinking water for 10 weeks. The ALA [100 mg/kg/day; 0.2% (w/w) in diet] was administered in last 5 weeks of experimental period. Results: Oxidative stress in liver tissue from hyperthyroid rats was accentuated. Significant increases in hepatic ROS, MDA, and PC levels were found. Additionally, increased FRAP and decreased GSH levels were observed. ALA treatment lowered the elevated serum free T3 and T4 levels and significantly decreased hepatic ROS, MDA and PC levels. Serum liver function tests in hiperthyroid rats before and after ALA treatment were not changed. Conclusion: Our results indicate that ALA treatment was effective in the improvement of changes in prooxidant-antioxidant balance, and may be useful as supportive agent for the treatment of hypertyroidism.