Changes in Lipid Peroxidation, Free Radical Scavengers and Tumour Necrosis Factor-alpha in Serum of Wistar Rats with Induced Thyroid Dysfunction

Aim: To assess the changes in lipid peroxidation, free radical scavengers and tumour necrosis factor-alpha in serum of Wistar rats with induced thyroid dysfunction.

Study Design: An experimental animal study was conducted in which Wistar rats with induced thyroid dysfunction were studied.

Place and Duration of Study: Animal House, Faculty of Pharmaceutical Sciences, Usmanu Danfodiyo University, Sokoto and Department of Chemical Pathology, Faculty of Medical Laboratory Sciences, Usmanu Danfodiyo University, Sokoto, between June, 2016 and December, 2016.

Methodology: Twenty-one (21) male Wistar rats weighing 140 - 180 grams were randomly divided into three groups. Therefore, each group consists of 7 rats. Euthyroid (control): untreated receiving daily intraperitoneal injection of 0.9% normal saline solution; hypothyroid: treated with daily oral administration of 6-propyl-2-thiouracil (5 mg/100 g) and hyperthyroid: treated with daily intraperitoneal injection of L-thyroxine (0.1 µg/g). At the end of the 30 days treatment, rats were fasted for 12 hours and blood samples were collected under chloroform anaesthesia for the estimation of serum total triidothyronine (tT3), total tetraiodothyronine (tT4), thyroid stimulating hormone (TSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), malondialdehyde (MDA) and tumour necrosis-alpha (TNF-α) using standard techniques. The rats were then scarified by cervical decapitation and slices of liver tissue were made for histological examination.

Results: The result indicated that final body weight, and serum tT3, tT4, SOD, CAT and GPX were significantly (P<0.05; P< 0.001) lower in hypothyroid and hyperthyroid rats while, serum MDA and TNF-α were significantly (P<0.05; P< 0.001) higher in hypothyroid and hyperthyroid compared with euthyroid rats. Serum TSH was significantly (P< 0.001) higher in hypothyroid compared with euthyroid and hyperthyroid rats. Histological examination of the hepatocellular tissue of euthyroid rat revealed normochromic and normocytic cellular architecture. There was polymorphocytic infiltration with mild inflammation and hypochromatic liver in hypothyroid rats while, conspicuous infiltrations of polymorphs in all fields were observed in hyperthyroid rats.

Conclusion: In this study, serum MDA and TNF-α were significantly higher, and SOD, CAT and GPX activities were lower in experimental hypothyroid and hyperthyroid rats. The result therefore suggests that a decreased antioxidant capacity coupled with increased oxidative stress and TNF-α may play an important role in the pathogenesis of hepatic injury due to thyroid dysfunction and underscores the role of antioxidants in reducing oxidative stress associated with thyroid dysfunction.