Protective Effects of Selenium and Zinc Against Nickel Chloride-Induced Hormonal Changes and Oxidative Damage in Thyroid of Pregnant Rats

Nickel chloride (NiCl2) is a heavy metal that may affect the function of the thyroid. Selenium (Se) and zinc (Zn) are essential trace elements involved in thyroid hormone metabolism. However, little is reported about thyrotoxicity during gestation. The current study aimed to investigate the protective effects of selenium and zinc against NiCl2-induced thyrotoxicity in pregnant Wistar rats. Female rats were treated subcutaneously (s.c.) on the 3rd day of pregnancy, with NaCl 0.9% and served as control, NiCl2 (100 mg/kg body weight (BW)) alone, or in association with Se (0.3 mg/kg, s.c.), ZnCl2 (20 mg/kg, s.c.), or both of them simultaneously. Oxidative stress parameters, thyroid biomarkers, and histopathological examination were evaluated. Results showed that NiCl2 exposure caused a significant decrease in maternal body weight and an increase in absolute and relative thyroid weight compared to the controls. NiCl2 administration also led to decreased plasma triiodothyronine (T3) and thyroxine (T4) with a concomitant significant increase in thyroid-stimulating hormone (TSH) levels when compared to that of control. In addition, an overall pro-oxidant effect was associated with a decrease in the reduced glutathione (GSH) and nonprotein thiol (NPSH) contents and the enzymatic activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD), and an increase in malondialdehyde (MDA). These biochemical disturbances were confirmed by histological changes. However, the co-treatment of Se and/or ZnCl2 attenuates NiCl2-induced changes. Our findings suggested that Se and ZnCl2 ameliorated NiCl2-induced thyrotoxicity in pregnant Wistar rats by exhibiting antioxidant effects.