Metabolic differences and similarities of selenium in blood and brain of the rat following the administration of different selenium compounds.

A common intermediate, i.e., selenite, was found in the serum of the rat; the maximum levels occurred 3 h after administration independent of chemical forms. This indicates that both the reduction of selenate to selenite, and oxidation of seleno-dl-methionine to selenite existed in the metabolic pathways of the rat. We found that water-soluble selenium compounds led to a similar maximum content in blood and serum, but seleno-dl-methionine had a higher affinity for the brain and, by gel filtration chromatography, for the higher mol-wt (25-100 K Da) fractions of serum protein, when compared with inorganic forms.