谷胱甘肽与蛋氨酸对饮水砷暴露小鼠体内砷化物的分布和甲基代谢的影响

Effect of glutathione and methionine on the distribution and methylic metabolism of arsenic speciation in mice exposed to arsenic through drinking water

目的探讨外源性谷胱甘肽(glutathione,GSH)和L-蛋氨酸(L-Methionine,L-Met)干预后,对饮水砷暴露小鼠肝、肾和血中化物的分布和甲基代谢的影响。方法将实验小鼠随机分为对照组(Con组)、单纯染砷组(As组)、GSH干预组(GSH组)与L-Met干预组(L-Met组)。小鼠自由饮用含砷50mg/L的水。从第4周起,染砷组同时腹腔注射GSH和L-Met进行处理,共处理7天。末次注射后24h处死小鼠,取其肝、肾和血组织样品。采用氢化物发生-超低温捕集-原子吸收分光光度法分别检测小鼠肝、肾和血中无机砷(inorganic arsenic,iAs)、一甲基胂(monomethylarsenic acid,MMA)和二甲基胂(dimethylarsenic acid,DMA)含量。结果L-Met组小鼠肝中DMA含量和砷二甲基化率(SMI)显著高于As组;GSH干预组小鼠肝中砷一甲基化率(PMI)和SMI显著高于As组。L-Met组和GSH组小鼠血中DMA、总砷含量和PMI均显著高于As组。结论GSH和L-Met对小鼠体内的砷甲基化代谢具有促进作用、可加速无机砷在体内的甲基化过程,最终使砷甲基代谢的终产物DMA含量增加,从而促进了总砷的代谢与排泄。

Objective To explore the effect of glutathione and L-methionine on the distribution and methylic metabolism of arsenic speciation in the liver, blood and kidney of mice exposed to inorganic As through drinking water. Methods Mice were randomly divided into control groups （Con）, the only groups with arsenic （As group）, GSH intervention groups （GSH） and L-Met intervention groups （L-Met）. The mice of experimental groups were exposed to arsenite by drinking water at the concentration of 50 mg/L arsenite for 4 weeks. The GSH groups and the L-methionine groups were injected with glutathinone and L-methioninerespectively on the fifth week. Livers, bloods and kidneys were taken to determinate the concentrations of inorganic （ iAs）, monomethylarsenic acid （MMA） and dimethylarsenic acid （DMA） using hydride generation trapping by ultra-hypothermia coupled with atomic absorption spectrometry. Results In liver, contents of DMA in L-methionine groups were moer higher than those of the As group. The primary methylic indexes （PMI） of arsenic speciation in the GSH groups and the secondary methylic indexex （SMI） of arsenic speciation in the GSH groups and L-methionine groups were more higher than those of the As group. In blood, contents of DMA and the total arsenic speciation （TAs） in both GSH groups and L-methionine groups were more higher than those of the As group. The PMI of arsenic speciation in both GSH groups and L-methionine groups were more higher than those of the As group. Conclusion GSH and L-methionine could promote the methyee metabolism of iAs. As a result, the content of DMA, the end product of methylated metabolism of arsenic, rises, which facilitates the methylic metabolism and excretion of iAs.