Role of copper in the regulation and accumulation of superoxide dismutase and metallothionein in rat liver
1988
Chung, K. | Romero, N. | Tinker, D. | Keen, C.L. | Amemiya, K. | Rucker, R.
Weaning male Sprague-Dawley rats were fed one of four diets that varied in Cu, Zn or Cd content. To the control diet (1) Cu, Zn and Cd were added at10, 100 and 0 mg/kg diet, respectively. Diets II and III also contained 10 mg/kgof dietary Cu, except that Zn was elevated to 1000 mg/kg for diet II, or Cd was added at 10 mg/kg for diet III. Diet IV was deficient in Cu (<1mg/kg) with Zn at100 mg/kg and no added Cd. At wk 6 postweaning, half of the rats fed diets I andIV were injected once with Cd acetate (5 mg Cd/kg body weight). The immediate response to Cd injection was an increase in metallothionein accumulation (three-tofourfold) and in Cu,Zn superoxide dismutase (SOD) accumulation (1.2-to 1.5-fold)in lever. SOD was estimated inan ELISA. These responses were not influenced by a change in Cu status (1vs.IV).However, in functional assays, SOD enzymatic activity was about half that of thecontrol values. In this regard,SOD appears to be given high priority with respect to the utilization of cellular Cu, i.e., a 10-fold reduction in hepatic Cu only resulted in a twofold reduction in SOD activity and the amount of apoenzyme remained at normal levels.
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