Importance of molar ratios in selenium-dependent protection against methylmercury toxicity

The influence of dietary selenium (Se) on mercury (Hg) toxicity was studied in weanling male Long Evans rats. Rats were fed AIN-93G-based low-Se torula yeast diets or diets augmented with sodium selenite to attain adequate- or rich-Se levels (0.1, 1.0 or 15 micromol/kg, respectively) These diets wer...

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Bibliographic Details
Published in:Biological trace element research 2007-12, Vol.119 (3), p.255-268
Main Authors: Ralston, Nicholas V C, Blackwell, 3rd, J Lloyd, Raymond, Laura J
Format: Article
Language:English
Subjects:
Animals
Brain - metabolism
Diet
Hair - chemistry
Male
Mercury
Mercury - blood
Mercury - metabolism
Mercury - toxicity
Methylmercury
Methylmercury Compounds - blood
Methylmercury Compounds - metabolism
Methylmercury Compounds - toxicity
Models, Biological
Rats
Rats, Long-Evans
Rodents
Selenium
Selenium - blood
Selenium - metabolism
Time Factors
Torula
Toxicity
Yeasts
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Summary:The influence of dietary selenium (Se) on mercury (Hg) toxicity was studied in weanling male Long Evans rats. Rats were fed AIN-93G-based low-Se torula yeast diets or diets augmented with sodium selenite to attain adequate- or rich-Se levels (0.1, 1.0 or 15 micromol/kg, respectively) These diets were prepared with no added methylmercury (MeHg) or with moderate- or high-MeHg (0.2, 10 or 60 micromol/kg, respectively). Health and weights were monitored weekly. By the end of the 9-week study, MeHg toxicity had impaired growth of rats fed high-MeHg, low-Se diets by approximately 24% (p < 0.05) compared to the controls. Growth of rats fed high-MeHg, adequate-Se diets was impaired by approximately 8% (p < 0.05) relative to their control group, but rats fed high-MeHg, rich-Se diets did not show any growth impairment. Low-MeHg exposure did not affect rat growth at any dietary Se level. Concentrations of Hg in hair and blood reflected dietary MeHg exposure, but Hg toxicity was more directly related to the Hg to Se ratios. Results support the hypothesis that Hg-dependent sequestration of Se is a primary mechanism of Hg toxicity. Therefore, Hg to Se molar ratios provide a more reliable and comprehensive criteria for evaluating risks associated with MeHg exposure.
ISSN:0163-4984
1559-0720
DOI:10.1007/s12011-007-8005-7