Selenium supplementation during cadmium exposure: Changes in antioxidant enzymes and the ultrastructure of the kidney

Abstract

Cadmium exposure in mice (8 mg Cd as CdCl2/kg bw, for 8 weeks, daily oral) resulted in increased cadmium levels in kidney and liver. The level was quite high in kidney (3 times) as compared to liver. However when selenium (0.35 mg Se as Na2SeO3/kg bw, daily, orally for 8 weeks) was administered concurrently, a significant decrease in cadmium level was seen in kidney and liver. Cadmium exposure resulted in apparent pathological changes in the proximal convoluted tubules (PCT) in kidney at the electron microscopic level. The mitochondria seem to be most severely affected among the cellular organelles. The alterations included swelling and dilation of the organelles. The cristae showed a disorganized architecture. Activities of the antioxidant enzymes glutathione peroxidase (GSH-Px) and catalase in kidney were also significantly inhibited. However, when selenium was co-administered, the structural integrity of the PCT was comparable to the control. The activity of the antioxidant enzymes was also restored to normal levels. This study suggests that cadmium manifests toxic effects by disrupting the antioxidant enzyme system, which in turn affects the membranous structures such as mitochondria and endoplasmic reticulum. This, in turn, affects the oxidative phosphorylation. Further, it is observed that the co-administration of selenium diminishes the effects of cadmium. J. Trace Elem. Exp. Med. 10:233–242, 1997. © 1997 Wiley-Liss, Inc.