REDOX MODULATION OF SELENIUM BINDING-PROTEINS BY CADMIUM EXPOSURES INMICE

The mechanism of the antagonistic behaviour of selenium (Se) against c admium (Cd) toxicity is investigated. This study reports the distribut ion of Cd at the organ and subcellular level after chronic treatments. The possible role of the selenium binding proteins (SEP) during Cd ex posure are also evaluated. Kidney concentrates more Cd than liver foll owing 8 weeks of treatment. Simultaneous administration of Se reduced Cd accumulation in Kidney. This affect did not occur in liver. Among t he subcellular fractions, the maximum concentrations of both of the el ements were found in the cytosol. The overall uptake of Se-75 was enha nced in the cytosol of kidney and liver of the Cd treated animals. The se observations support a hypothesis that selenium is complexed with c admium. The increase in the labeling of SBP as a result of Cd exposure s may reflect a change in the conformation of the protein molecule. Th ese proteins (SEP) contain a sequence motif, which may be an active re dox centre. Also, Cd significantly reduced the glutathione level, ther eby disrupting the thiol/disulfide balance. This ia turn may affect th e redox status of the proteins leading to a Se-75 or Se-75-Cd complex with SBP.