Tissue content of mercury in rats given methylmercuric chloride orally: influence of intestinal flora.
The effect of intestinal flora on the absorption and dispositon of mercury in tissues was investigated using conventional rats, and rats treated with Antibiotics
to eliminate their gut flora. Antibiotic-treated rats given [203Hg]-labeled methylmercuric chloride orally had significantly more mercury in their tissues, especially in kidney, brain, lung, blood, and skeletal muscle, and also excreted less mercury in the feces than conventional rats. Furthermore, in the kidneys of the antibiotic-treated rats, the proportion of mercury present as organic mercury was greater than in the kidneys of the conventional rats. The results suppport the hypothesis that the metabolism of methylmercuric chloride by the gut flora reduces the tissue content of mercury. When rats were administered 10 mg methylmercuric chloride/kg . day for 6 days, four of five of those given Antibiotics
developed neurological symptoms of toxicity, whereas only one of five conventional rats given methylmercuric chloride was affected.
rats given methylmercuric chloride orally: influence of intestinal flora
Effects of diet on mercury metabolism and excretion in mice given methylmercury: role of gut flora.
Mice fed either (1) a pelleted rodent diet, (2) evaporated milk, or (3) a synthetic diet (high protein, low fat) exhibited different rates of whole body mercury elimination and fecal mercury excretion after exposure (per os) to methylmercuric chloride. The percentage of the total mercury body burden present as mercuric mercury was highest (35.3%) in mice fed the synthetic diet (which had the highest rate of mercury elimination) and lowest (6.6%) in the animals having the lowest mercury elimination rate (milk-fed mice). Mice fed the synthetic diet had lower mercury concentrations and had a higher proportion of mercuric mercury in their tissues than the mice from the other dietary groups. Treatment of the mice with Antibiotics
throughout the experimental period to suppress the gut flora reduced fecal mercury excretion and the dietary differences in whole body retention of mercury. Tissue mercury concentrations and proportion of organic mercury in feces, cecal contents, liver, and kidneys were increased by Antibiotic
treatment of mice fed the pelleted or synthetic diets. These results are consistent with the theory that demethylation of methylmercury by intestinal microflora is a major factor determining the excretion rate of mercury.
mercury metabolism and excretion in mice given methylmercury: role of gut flora