Metallothionein I and II protect against zinc deficiency and zinc toxicity in mice

J Nutr. 1996 Jul;126(7):1782-90. doi: 10.1093/jn/126.7.1782.


Metallothionein (MT)-bound zinc accumulates when animals are exposed to excess zinc and is depleted under conditions of zinc deficiency, suggesting that MT serves as a means of sequestering excess zinc as well as a zinc reservoir that can be utilized when zinc is deficient. To examine the importance of MT for these processes, mice with null alleles of both MT I and MT II genes were created and the zinc concentration and histological appearance of multiple organs assessed. At birth, the hepatic zinc concentration of these MT-null mice was lower than that of wild-type controls (0.27 +/- 0.02 vs. 0.65 +/- 0.11 micromol zinc/g tissue, P < 0.05). During the next 3 wk of suckling zinc-replete (95 micrograms zinc/g diet) dams, the hepatic zinc concentration of controls fell to 0.42 +/- 0.04 micromol/g but was unchanged in the MT-null mice (0.28 +/- 0.04 micromol/g). The most prominent histological anomaly observed at 3 wk of age was the presence of swollen Bowman's capsules in the kidneys of MT-null mice. When nursing MT-null dams were fed a severely zinc-deficient (1.5 microg/g) diet, kidney development in the MT-null pups was retarded as indicated by the retention of the nephrogenic zone and incomplete tubule development. We suggest that the lack of a hepatic reservoir of zinc jeopardizes the developing kidney in the MT-null mice. In addition to being more sensitive to dietary zinc restriction, MT-null mice are more sensitive to zinc toxicity. When adult mice were challenged with a ramping dose of zinc up to a total of 3700 micromol zinc/kg body weight, MT-null mice had a greater incidence of pancreatic acinar cell degeneration compared with control mice despite accumulating less zinc (2.72 +/- 0.46 vs. 1.23 +/- 0.52 micromol zinc/g pancreas, control and MT-null, respectively, P < 0.05). The results of these experiments suggest that MT I and MT II can protect against both zinc deficiency and zinc toxicity.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Body Weight / drug effects
  • Bone and Bones / metabolism
  • Diet
  • Genotype
  • Kidney / metabolism*
  • Kidney / pathology
  • Liver / metabolism*
  • Male
  • Metallothionein / biosynthesis
  • Metallothionein / physiology*
  • Mice
  • Mice, Knockout
  • Pancreas / drug effects
  • Pancreas / pathology
  • Zinc / deficiency*
  • Zinc / toxicity*


  • Metallothionein
  • Zinc