Reversal of Cadmium-Induced Thyroid Dysfunction by Selenium, Zinc, or Their Combination in Rat

Abstract

The aim of this study was to evaluate the potential benefit of combined treatment with zinc (Zn) and selenium (Se) in reversing cadmium (Cd)-induced thyroid dysfunction compared to Se or Zn treatment alone in rats exposed to Cd. For this purpose, 30 adult male Wistar albino rats were equally divided into control and four treated groups receiving either 200 ppm Cd (as CdCl2), 200 ppm Cd + 500 ppm Zn (as ZnCl2), 200 ppm Cd + 0.1 ppm Se (as Na2SeO3), or 200 ppm Cd + 500 ppm Zn + 0.1 ppm Se in their drinking water for 35 days. The results showed that Cd exposure increased significantly the relative thyroid weight (RTW), the thyroid Cd concentration, and the serum thyroid stimulating hormone (TSH) level, whereas the serum thyroxine (T4) level was decreased compared to control rats. The treatment of Cd-exposed rats with Se alone only partially protected from the Cd-induced decrease in serum T4 level. The treatment of Cd-exposed animals with Zn alone partially protected against Cd-induced thyroid dysfunction by maintaining normal RTW and by decreasing Cd concentration in the thyroid. It also partially prevents Cd-induced decrease in serum T4 level. The combined treatment of Cd-exposed animals with Se and Zn induced a more significant decrease in the thyroid Cd concentration than the Zn supplement and a total correction of the RTW. This treatment was also more effective than that with Se or Zn alone in reversing Cd-induced decrease in serum T4 level and Cd-induced increase in serum TSH level. Se and Zn can have a synergistic role against Cd-induced thyroid dysfunction.

Effect of Selenium on Chlorpyrifos-Induced Thyroid Toxicity in Albino Rats

“…It has been demonstrated that Se has a central role as supplementary therapy in Graves's disease because of its action through selenoenzymes both on transforming of the thyroid hormones and on the antioxidative defense of the organism (Vrca et al2004). Hammouda et al (2008) reported that the treatment of cadmium-exposed rats with Se partially protected from the cadmium induced decrease in serum T4 level and increase in serum TSH level.…”

Cadmium and Selenium Interaction in Mammals

“…Nađene su snižene razine lipidne peroksidacije pri istodobnom izlaganju Se i Cd u odnosu na životinje izložene samo Cd (116)(117)(118). Schrauzer (119) našao je u istraživanjima na miševima da kronična izloženost niskim dozama Cd (i nekih drugih metala) poništava zaštitni učinak koji Se ima na pojavu raka.…”

Can zinc supplementation ameliorate cadmium-induced alterations in the bioelement content in rabbits?

“…There are also examples of a significant association between Cd and myocardial infarction (2) as well as between Cd and prediabetes and diabetes mellitus in humans (3). Furthermore, cadmium acts as an inorganic xenoestrogen in humans: there is evidence that Cd possesses estrogenic activity (4,5), while its thyroid-disrupting activities have been observed in experimental studies (6)(7)(8).…”