Possible Mechanism of Detoxifying Effect of Selenium on the Toxicity of Mercury Compounds

Abstract

Co-administration of selenium compounds with mercuric mercury resulted in remarkable depression of acute toxicity of mercury through 1) reduction of mercury accumulation in the kidneys, a major target of acute toxicity of inorganic mercury, by forming high molecular weight complexes consisting of Hg, Se and proteins in the blood, which were hardly filtered through glomerulus; 2) elongation of retention of mercury and selenium as inert high molecular weight complexes in the blood, especially in the erythrocytes; 3) fom1ation of stable and non-diffusible complexes of Hg and Se in various organs such as the liver and kidneys.Methylmercury was found to fom1 a complex with selenium, bis(methylmercuric) selenide (BMS) , in various tissues on concurrent administration with selenite.However, the reduction of methylmercury toxicity by selenium as reported in numerous papers seems to be hardly explainable by the formation of BMS which showed a relatively low stability in the blood and other tissues.Using the assay methods developed in the studies described above to detect interactions between selenium and other metals, we indicated that more than 18 metal ions might be subjected to interactions with selenium in animal body, showing important roles of this essential metalloid as a modifying factor of metal toxicity. Although, according to the experimental data so far obtained, selenium appears not to 275 T. Suzuki et al. (eds.), Advances in Mercury Toxicology

Mercury–Selenium Species Ratio in Representative Fish Samples and Their Bioaccessibility by an In Vitro Digestion Method

“…As reported by Parizek and Ostadalova [6], and subsequently confirmed by many other researchers, simultaneous administration of selenite counteracts the negative impacts of exposure to inorganic Hg, particularly in regard to neurotoxicity, fetotoxicity, and developmental toxicity [7]. In addition to the antagonism by Se of the toxicity of inorganic Hg, its detoxifying effect on methylmercury has attracted the attention of many scientists in heavy metal toxicology [8].…”

Gestational exposure to methylmercury and selenium: Effects on a spatial discrimination reversal in adulthood

“…Fish consumption is the primary source of human exposure to methylmercury, a known developmental neurotoxicant (Clarkson, 2002;Schober, 2003), but fish are also a source of important nutrients such as selenium (Chapman and Chan, 2000). When administered concurrently with methylmercury, selenium confers some protection against certain neurological effects of chronic, high-level MeHg exposure (Magos, 1991;Moller-Madsen and Danscher, 1991) even as it elevates mercury concentration in many regions of the nervous system (Imura and Naganuma, 1991;Moller-Madsen, 1994;Moller-Madsen and Danscher, 1991;Prohaska and Ganther, 1977;Thomas and Smith, 1984), as well as in blood, liver, and testes (Whanger, 1992).…”

In UteroMethylmercury Exposure Differentially Affects the Activities of Selenoenzymes in the Fetal Mouse Brain

“…To establish the relationship between mercury and the neurobehavioral outcome, many confounding factors need to be taken into account (Grandjean and Weihe, 1993). Among the potential confounding factors is selenium (Se), for which toxicological interactions with mercury have long been known (Imura and Naganuma, 1991).…”

“…For example, the acute interaction between toxic doses of inorganic mercury and toxic doses of selenite in adult rodents has been thoroughly examined and can be described as a mutual alleviation of toxicity, through the formation of an inert Hg-Se complex (Imura and Naganuma, 1991). On the other hand, only a few studies have addressed the interaction between MeHg and the dietary-derived (or the physiological level of ) selenium during the prenatal period, which is much more relevant to the situation encountered in fish-eating populations.…”