McCormick C C, Menard M P, Cousins R J
Am J Physiol. 1981 Apr;240(4):E414-21. doi: 10.1152/ajpendo.1981.240.4.E414.
Induction of hepatic metallothionein was investigated in zinc-depleted rats after a single feeding (via stomach tube) of a complete diet with or without supplemental zinc. Subsequent to a maximum elevation in serum zinc (3.25 micrograms/ml) at 3 h, the rate of metallothionein synthesis increased 4.5-fold by 10 h after feeding. Changes in the rate of metallothionein synthesis coincided with similar changes in the level of translatable mRNA coding for metallothionein. Accumulation in liver of Zn2+ as metallothionein rose to a maximum by 12 h after diet administration and thereafter remained constant. Radioactive zinc (65Zn) included in the diet rapidly associated with newly formed metallothionein. Unlike Zn2+, 65Zn exhibited marked fluctuations within the 24-h period following feeding, indicating that zinc associated with metallothionein may be capable of exchange and/or dissociation. Changes in total liver 65Zn were accompanied by concomitant changes in metallothionein-bound 65Zn. This study has related (temporally) the metabolism of dietary zinc to the induction, apparently via transcription of mRNA, of hepatic metallothionein.
在给缺锌大鼠经胃管单次喂食含或不含补充锌的全价日粮后，对肝脏金属硫蛋白的诱导情况进行了研究。喂食后3小时血清锌达到最高值（3.25微克/毫升），之后金属硫蛋白的合成速率在喂食后10小时增加了4.5倍。金属硫蛋白合成速率的变化与编码金属硫蛋白的可翻译mRNA水平的类似变化相一致。作为金属硫蛋白的Zn2+在肝脏中的积累在日粮投喂后12小时达到最大值，此后保持恒定。日粮中所含的放射性锌（65Zn）迅速与新形成的金属硫蛋白结合。与Zn2+不同，65Zn在喂食后的24小时内表现出明显的波动，这表明与金属硫蛋白结合的锌可能能够交换和/或解离。肝脏中总65Zn的变化伴随着金属硫蛋白结合的65Zn的相应变化。本研究在时间上关联了日粮锌的代谢与肝脏金属硫蛋白的诱导，这种诱导显然是通过mRNA转录实现的。
