Comparative Effects of Bisphenol A, Carbimazole and Thyroxine Administration on the Thyroid Gland, Serum Selenium and Iodine Concentration of Wistar Rats

The effects of Bisphenol A (BPA), carbimazole and thyroxine on thyroid gland were investigated in 40 Wistar rats assigned as untreated controls, BPA (20 µg/kg/day), carbimazole (5 mg/day), and thyroxine (25 µg/day) orally by gavage. Each group contained 10 rats, 5 males and 5 females. BPA and carbimazole caused hypothyroidism within 30 days. The concentrations of T3 and T4 were lower (P<0.05-0.001) in the groups received BPA and carbimazole, respectively, in both males and females. Significant increases (P<0.05-0.01) of the two hormones were observed in rats given thyroxine at 25µg/day than the control rats. TSH concentration decreased (P<0.01) in the rats received thyroxine, while significant increases (P<0.05-0.01) were observed in the rats received BPA and carbimazole, respectively, than the controls. Thyroxine was found to induce hyperthyroidism as evidenced by elevation of T4 and T3 with a significant decrease of TSH. The concentrations of selenium and iodine were lower (P<0.05-0.01) in the test groups of both sexes than the control rats. The group received thyroxine, scored the lowest selenium concentration of all the other test groups and significantly lower (P<0.01) than the control, while those received carbimazole showed lower (P<0.05-0.01) iodine levels. No change was observed in the iodine level of the female rats received thyroxine. Alteration in serum thyroid hormones, selenium and iodine concentrations were corelated with changes in thyroid histological structure. Only on rat of BPA received group died one day before the end of the experimental period.