Availability and metabolism of {sup 77}Se-methylseleninic acid compared simultaneously with those of three related selenocompounds
- Graduate School of Pharmaceutical Sciences, Chiba University, Chuo, Chiba 260-8675 (Japan)
Nutritional selenocompounds are considered to be transformed into the common intermediate selenide for utilization as selenoenzymes and/or for excretion as selenosugar and trimethylselenonium (TMSe). Therefore, selenocompounds can only be traced with a labeled selenium atom. Methylseleninic (MSA{sup IV}) has been proposed to be a third nutritional selenium source, the other two being inorganic selenocompounds and organic selenoamino acids, and to be a proximate selenochemical for producing the assumed biologically active form methylselenol. Here we applied a new tracer method to compare the availability and metabolism of MSA{sup IV} with those of three related selenocompounds under exactly identical host and tracing conditions. {sup 82}Se-Selenite, {sup 78}Se-selenate, {sup 77}Se-MSA{sup IV} and {sup 76}Se-methylselenonic acids (MSA{sup VI}) were simultaneously administered orally, each at the dose of 25 {mu}g Se/kg body weight, to rats that had been depleted of endogenous natural abundance selenium with a single stable isotope ({sup 8}Se). Time-related changes in the concentrations and/or distributions of the four labeled isotopes in the serum, liver, kidney, pancreas, lung and urine were determined simultaneously by inductively coupled argon plasma mass spectrometry (ICP MS) and/or HPLC-ICP MS. The availability with different isotope ratios was in the decreasing order of selenate > selenite = MSA{sup IV} > MSA{sup VI}. Although selenate and MSA{sup VI} were distributed in organs and urine partly in their intact forms, MSA{sup IV} and selenite were not detected in the intact forms at all. MSA{sup IV} and MSA{sup VI} but not selenite or selenate produced TMSe in organs other than the liver, suggesting the transformation of MSA{sup IV} into methylselenol, and then either into selenide for the synthesis of selenoproteins and selenosugar or directly into TMSe. Thus, selenosugar and TMSe were produced widely in the organs. However, TMSe was not detected in the liver. The organ- and selenium source-specific production of TMSe was discussed as to the differences in selenium sources, and demethylation and methylation activity.
- OSTI ID:
- 20850478
- Journal Information:
- Toxicology and Applied Pharmacology, Vol. 217, Issue 1; Other Information: DOI: 10.1016/j.taap.2006.07.005; PII: S0041-008X(06)00249-3; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0041-008X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Methylation and demethylation of intermediates selenide and methylselenol in the metabolism of selenium
Preferential organ distribution of methylselenol source Se-methylselenocysteine relative to methylseleninic acid