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KMID : 0382420010270020082
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Korean Journal of Environmental Health Society
2001 Volume.27 No. 2 p.82 ~ p.91
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A Study on the Protective Effect and Its Mechanism of Zinc against Immuno-cytotoxicity of Methylmercury
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Koh Dai-Ha
Youm Jung-Ho
Oh Gyung-Jae
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Abstract
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This study was carried out to elucidate the protective effect of zinc chloride(ZnCl_2) and its mechanism against the immuno-cytotoxicity of methylmercury chloride(CH_3HgCl).
This study was observed in the culture of EMT-6 cells which are originated from mammary adenocarcinoma of Balb/c mouse. Cytotoxicity of metals was measured by cell viability and NO_2^-, and mitochondrial function was evaluated by adenosine triphosphate (ATP) production.
CH-3HgCl significantly decreased the synthesis of nitric oxide(NO), ATP and glutathione(GSH) in a dosedependent manner. ZnCl_2 significantly increased the synthesis of GSH in a dose-dependent manner, but synthesis of NO and ATP were not changed.
The immuno-cytotoxicity of CH_3HgCl was not fully protected when combined addition of ZnCl_2, whereas ZnCl_2 prior to addition of CH_3HgCl completly protected the Hg-induced immuno-cytotoxicity. Similarly, intracellular accumulation of mercury significantly decreased by ZnCl_2. Degree of diminution of intracellular mercury was larger in ZnCl_2 prior to addition of CH_3HgCl than in combined addition of ZnCl_2 and CH_3HgCl.
Dithiothreitol(DTT) or buthionine sulfoximine(BSO) addition at 50 μ M or less, which was not toxic to the cells, did not affect synthesis of NO and ATP. DTT increased intracellular GSH level and DTT pretreatment protected toxicity induced by CH_3HgCl as shown complete recover in the NO and ATP values. BSO decreased intracellular GSH level and BSO pretreatment exaggerated toxicity induced by CH_3HgCl as shown synergistic reduction in the NO and ATP values.
These results indicated that the protective effects of zinc against immuno-cytotoxicity of methylmercury associated with increasing cellular level of GSH. Increased intracellular GSH transports methylmercury to out of cells. In accordance with intracellular level of mercury decreased, immuno-cytotoxicity of methylmercury decreased.
These results also suggest that the protective mechanism of zinc against the mercury toxicity would be exerted in the immune system in vivo.
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