SELENIUM INFLUENCES TISSUE-LEVELS OF SELENOPROTEIN-W IN SHEEP

Because selenium increases the levels of other selenoproteins, the inf luence of this element on selenoprotein W was examined in wether sheep fed either a low selenium diet (0.02 mg/kg) or the same diet suppleme nted with 3 mg selenium as selenite per kilogram diet. Muscle biopsies were taken initially and at 3.5, 7.0 and 10.5 wk. The sheep were kill ed after the last muscle biopsy and samples from nine tissues were tak en. Selenoprotein W was determined in tissues by Western blots with a polyclonal antibody against a synthetic peptide based on the protein s equence of the homologous rat selenoprotein W. In supplemented sheep, muscle selenoprotein W was significantly increased over initial levels (P < 0.05) at 7 wk and afterwards, whereas in sheep consuming the low selenium diet, muscle selenoprotein W levels declined significantly ( P < 0.05) after 10.5 wk. This selenoprotein was found in various amoun ts in all tissues examined. The highest levels of selenoprotein W were found in skeletal muscles and heart and the lowest was found in liver . Except for selenoprotein W in brain, the concentrations of selenopro tein W, selenium and glutathione peroxidase activity were significantl y higher (P < 0.05) in all tissues from supplemented sheep than in tho se from unsupplemented sheep. The selenoprotein W levels in brains of the two groups were not significantly different. Thus, selenoprotein W levels in all tissues of sheep except the brain are sensitive to sele nium status.