Metabolic pathway of inorganic and organic selenocompounds labeled with stable isotope in Japanese quail.

ABSTRACT

The distribution and metabolism of an inorganic selenium (Se) compound and a selenoamino acid in quails were evaluated by speciation with inductively coupled plasma mass spectrometry (ICP-MS) and a stable isotope. Quails were orally administered stable isotope [(77)Se]-labeled selenite and selenomethionine (SeMet) at the nutritional dose of 10 µg Se/bird. Then, the quails were dissected 3, 9, and 24 h after the administration to examine the metabolic pathway and the time-dependent change of Se. The concentrations of exogenous Se in all the organs and tissues of the SeMet-administered group were significantly higher than those of the selenite-administered group 3 h after the administration. This suggested that SeMet was more rapidly and/or efficiently incorporated into the quail body than selenite. A Se-containing protein in the serum was detected only in the SeMet-administered quails, but not in the selenite-administered quails. The major urinary Se metabolite, i.e., Se-methylseleno-N-acetyl-galactosamine (selenosugar), was detected in the quail serum after the administration of both selenite and SeMet. The endogenous amount of Se-methylated selenosugar (MeSeSug) in the serum of quails seemed to be larger than that of the rodents. We conclude that the metabolic pathway of Se in quails was the same as that in rodents, but the metabolic capacity for Se seemed to be larger in quails than in rodents.