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

Watanabe, Chiho; Yoshida, Katsumi; Kasanuma, Yuichi; Yin, Kai; Satoh, Hiroshi

doi:10.1006/enrs.1998.3889

Cited by 116 publications

(66 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Whether this accumulation of MeHg in placenta causes any adverse effects in humans is not known. Studies on mice have shown effects on the activity of selenoenzymes, such as inhibition of glutathione peroxidase, although the placental concentration of selenium was not affected (33). Glutathione peroxidase is an antioxidative enzyme, and high levels are probably needed in the placenta to protect the fetus from the oxidative stress produced during the metabolism of MeHg (34).…”

Section: Discussionmentioning

confidence: 99%

Inorganic mercury and methylmercury in placentas of Swedish women.

Ask

Åkesson

Berglund

et al. 2002

Environ Health Perspect

147

View full text Add to dashboard Cite

We determined levels of inorganic mercury (I-Hg) and methylmercury in placentas from 119 Swedish women, not selected with respect to high exposure of mercury. Our objective was to relate placental Hg species with maternal and fetal blood concentrations and to evaluate possible associations with selenium. We performed the analyses using automated alkaline solubilization/reduction and cold-vapor atomic fluorescence spectrophotometry. I-Hg levels in placenta increased with an increasing number of maternal dental amalgam fillings (p < 0.001). Despite placental accumulation (median, 1.3 microg/kg; range, 0.18-6.7 microg/kg wet weight), a substantial fraction of maternal blood I-Hg, probably as Hg(0), reached the fetus. Although MeHg transferred easily to the fetus, it also accumulated in the placenta. On average, 60% of placental Hg was in the form of MeHg. The median concentration was 1.8 microg/kg (range, 0-6.2 microg/kg wet weight), more than twice the maternal blood concentration. We found significant associations between MeHg and selenium in both maternal and umbilical cord blood but not in the placenta. The associations were particularly obvious in freshwater fish consumers, probably reflecting that fish is a source of both MeHg and selenium. We found no correlations between I-Hg and selenium. This study increases the understanding of Hg, in its different forms, in human placenta and how they are related to maternal and fetal exposure.

show abstract

Section: Discussionmentioning

confidence: 99%

Inorganic mercury and methylmercury in placentas of Swedish women.

Ask

Åkesson

Berglund

et al. 2002

Environ Health Perspect

147

View full text Add to dashboard Cite

show abstract

“…Dietary selenium is postulated to protect against mercury toxicity and the mercury-dependent inhibition of selenoenzyme activity. Additional dietary selenium has been shown to offset the selenium sequestered by mercury and thereby maintain normal antioxidant activity of brain selenoenzymes [39][40][41][42][43][44] . Increasing blood Hg:Se ratios are indicative of increasing risk or harm, therefore, assessment of MeHg exposure should involve the evaluation of blood Hg:Se ratios, rather than mercury levels alone.…”

Section: Biological Functions Of Selenoneine In Fishmentioning

confidence: 99%

Discovery of the strong antioxidant selenoneine in tuna and selenium redox metabolism

Yamashita¹,

Yabu²,

Yamashita

2010

WJBC

103

View full text Add to dashboard Cite

A novel selenium-containing compound, selenoneine, has been isolated as the major form of organic selenium in the blood and tissues of tuna. Selenoneine harbors a selenium atom in the imidazole ring, 2-selenyl-N α, N α, N α-trimethyl-L-histidine, and is a selenium analog of ergothioneine. This selenium compound has strong antioxidant capacity and binds to heme proteins, such as hemoglobin and myoglobin, to protect them from iron auto-oxidation, and it reacts with radicals and methylmercury (MeHg). The organic cations/ carnitine transporter OCTN1 transports selenoneine and MeHg, regulates Se-enhanced antioxidant activity, and decreases MeHg toxicity. Thus, the dietary intake of selenoneine, by consuming fish, might decrease the formation of reactive oxygen radicals that could oxidize nucleotides in DNA, and thereby inhibit carcinogenesis, chronic diseases, and aging.

show abstract

“…Therefore, intracellular methylmercury tends to diminish the amount of selenium that is biologically available for normal selenoenzyme synthesis, especially as Hg:Se molar ratios approach or exceed a 1:1 stoichiometry. Protective effects of dietary selenium against mercury toxicity (Ganther et al, 1972;Prohaska and Ganther, 1977;Watanabe et al, 1999a,b;Ralston et al, 2007;Yang et al, 2008), and in prevention of mercury-dependent inhibition of selenoenzyme activities (Prohaska and Ganther, 1977;Watanabe et al, 1999b), appear to occur because additional dietary selenium is able to offset the selenium sequestered by mercury and thereby maintain normal antioxidant activities of brain selenoenzymes.…”

Section: Introductionmentioning

confidence: 99%