Selenium influences tissue levels of selenoprotein W in sheep

Because selenium increases the levels of other selenoproteins, the influence 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 supplemented 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 killed after the last muscle biopsy and samples from nine tissues were taken. Selenoprotein W was determined in tissues by Western blots with a polyclonal antibody against a synthetic peptide based on the protein sequence 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 amounts 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 selenoprotein W, selenium and glutathione peroxidase activity were significantly higher (P < 0.05) in all tissues from supplemented sheep than in those 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 selenium status.