Interaction between selenium and methylmercury.

Abstract

The available data on the influence of selenium on the toxicity of methylmercury and of methylmercury on selenium as a nutrient and toxic agent are reviewed. Selenium as selenite has a relative protective effect on acute and subacute toxicity of methylmercury in the rat and the quail. The protective mechanism is far from clear. Of special interest is the fact that selenium-treated animals may remain unaffected, even when they have attained tissue mercury levels otherwise associated with toxic effects. Selenite causes some increase of tissue mercury levels in methylmercury-exposed animals. On the other hand, methylmercury induces a remarkable enhancement of organ concentrations of selenium in animals given selenite. The interaction between selenium and methylmercury is in many ways different from that between selenium and inorganic mercury, and also from that between selenium and other metals. Due to the considerable interspecies differences in the toxicity of methylmercury, the available data do not allow conclusions on interactions in man. Practical implications of a possible protective effect of selenium on methylmercury toxicity in humans are discussed.

Selenium as an antidote in the treatment of mercury intoxication

“…Ganther et al (1972) were the first who reported that Se had a protective effect against MeHg toxicity. The same effect was later found in quail, chick, mice, rat, and cat (Ganther 1980;Magos and Webb 1980;Skerfving 1978). When MeHg is given in a single dose or a limited number of doses, selenite prevents the onset of neurological disorders effectively.…”

Selenoneine, a Novel Selenium-Containing Compound, Mediates Detoxification Mechanisms against Methylmercury Accumulation and Toxicity in Zebrafish Embryo

“…Following this line of thought, the MeHg complex may be decomposed to inorganic Hg, i.e., mercury selenide (HgSe). HgSe found in the liver of marine mammals (Friberg and Mottet 1989; Itano et al 1985; Ng et al 2001; Nigro and Leonzio 1996; Palmisano et al 1995; Skerfving 1978) may be produced from the selenoneine–MeHg complex by this OCTN1-mediated secretory lysosomal mechanism. In this study, however, no selenoneine–MeHg was detected in MeHg-exposed zebrafish embryos by LC-ICP-MS analysis.…”

“…Inorganic mercury (Hg) is distributed in marlin meat and in the livers and kidneys of fish and laboratory animals chronically exposed to MeHg (Clarkson 1972; Friberg and Mottet 1989; Itano et al 1985; Ng et al 2001; Nigro and Leonzio 1996; Palmisano et al 1995; Skerfving 1978). Although demethylation of MeHg is thought to be an important route of detoxification, the underlying molecular mechanism is poorly understood.…”

Mercury‐selenium compounds and their toxicological significance: Toward a molecular understanding of the mercury‐selenium antagonism

“…Several earlier reviews have examined possible mechanisms for the antagonistic effect between Hg and Se [55,56,[61][62][63], which are summarized in the six pathways detailed here: formation of MeHg-Se compounds, Se-aided demethylation of MeHg, formation of inorganic Hg-Se compounds, redistribution of inorganic Hg in the presence of Se, Se inhibition of methyl radicals from MeHg, and Hg-induced Se deficiency. The first four pathways are based on the assumption that the toxicity of Hg and MeHg is caused by the Hg 2ϩ or MeHg ϩ , whereas the last two pathways attribute the observed Hg toxicity, at least in part, to the methyl group and Se deficiency, respectively.…”