Effect of High Sensitive Factor on Distribution of Cadmium Using Iron-deficient Metallothionein-l/II Null Mice

我们利用缺铁的金属硫蛋白-L/II缺失型妊娠小鼠，研究了孕期镉暴露(50ppm)中金属硫蛋白和膳食铁对镉分布的影响。在镉暴露野生型小鼠中，低铁饮食组母肝、母肾和胎肝镉含量均显著高于正常铁饮食组。相比之下，在镉暴露的金属硫蛋白-L/II基因缺失小鼠中，低铁饮食组母鼠肝脏和肾脏中的镉浓度显著高于正常铁饮食组。而在镉暴露的金属硫蛋白-L/II基因缺失小鼠胎肝中，低铁饮食组与正常铁饮食组小鼠胎肝镉浓度无明显差异。此外，无论是低铁饲料组还是正常铁饲料组，金属硫蛋白-L/II基因敲除小鼠母鼠肝脏和肾脏镉含量均显著低于野生型小鼠，而胎肝镉含量明显高于野生型小鼠。而金属硫蛋白-L/II基因缺失小鼠的低铁饲料组、野生型小鼠的低铁饲料组、金属硫蛋白-L/II基因缺失小鼠的正常铁饲料组和野生型小鼠的正常铁饲料组胎盘中镉含量无差异。这些结果表明，金属硫蛋白和膳食铁在抑制镉在胎肝中的蓄积中起重要作用。在孕期镉暴露中，金属硫蛋白对小鼠胎鼠镉蓄积的影响强于膳食铁。

We examined the effects of metallothionein and dietary iron on the distribution of cadmium in exposure to cadmium (50 ppm) during gestation using the iron-deficient metallothionein-l/II null pregnant mice. In the cadmium-exposed wild-type mice, cadmium concentrations in the maternal liver, maternal kidney and fetal liver of low iron diet group significantly increased compared with those of normal iron diet group. In contrast, in the cadmium-exposed metallothionein-l/II null mice, cadmium concentrations in the maternal liver and kidney of low iron diet group were significantly higher than those of normal iron diet group. However, in the fetal liver of cadmium-exposed metallothionein-l/II null mice, cadmium concentration was not different between low iron diet group and normal iron diet group. Furthermore, in the both low iron diet group and normal iron diet group, cadmium concentrations in the maternal liver and kidney of metallothionein-l/II null mice exposed to cadmium markedly decreased compared with those of wild-type mice whereas cadmium concentration in the fetal liver of metallothionein-l/II null mice was significantly higher than that of wild-type mice. On the other hand, cadmium concentration in the placenta was not different between four groups, which are low iron diet group in metallothionein-l/II null mice, low iron diet group in wild-type mice, normal iron diet group in metallothionein-l/II null mice and normal iron diet group in wild-type mice. These results suggested that metallothionein and dietary iron plays an important role in the inhibition of cadmium accumulation in the fetal liver. In the gestational exposure to cadmium, effect of metallothionein on the cadmium accumulation in the fetus of mice was stronger than that of dietary iron.