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Selenium detoxification by methylation
B S Hassoun1, I S Palmer, C Dwivedi
1Station Biochemistry, South Dakota State University, Brookings 57007, USA.
Research Communications in Molecular Pathology and Pharmacology
|October 1, 1995
Summary
Selenium detoxification primarily occurs through methylation. This study investigated methyltransferase activity in rat liver, finding variations between strains and linking methylation to selenium
Area of Science:
- Biochemistry
- Toxicology
- Environmental Health
Background:
- Methylation is the primary detoxification pathway for selenium.
- Transmethylation, catalyzed by methyltransferases, is key for forming methylated compounds.
- Understanding methyltransferase activity is crucial for selenium toxicity research.
Purpose of the Study:
- To assay methyltransferase activity in liver cytosol from different rat strains.
- To investigate the role of methylation in selenium detoxification and toxicity.
- To compare selenium volatilization and lethal dose 50 (LD50) across rat strains.
Main Methods:
- Liver cytosol preparation from Fischer, Wistar, and Sprague-Dawley rats.
- High-Performance Liquid Chromatography (HPLC) assay to measure epinephrine formation from norepinephrine, indicating methyltransferase activity.
- Intraperitoneal injection of selenium (Se) to assess volatilization and determine LD50.
Main Results:
- Methyltransferase activity varied significantly among rat strains: Fischer (1.65 x 10^-12), Wistar (0.74 x 10^-12), and Sprague-Dawley (1.2 x 10^-12) moles epinephrine formed/mg protein/hr.
- Selenium volatilization was higher in Wistar rats compared to Fischer rats.
- LD50 values for Wistar and Fischer rats were 2.58 and 3.15 mg Se/kg, respectively.
Conclusions:
- Rat strain significantly influences methyltransferase activity and selenium metabolism.
- Enhanced methylation of dimethyl selenide to trimethyl selenide is likely a critical detoxification mechanism for selenium.
- Differences in methylation capacity may explain variations in selenium toxicity and tolerance among rat strains.