Zinc-copper interactions in the pregnant rat: fetal outcome and maternal and fetal zinc, copper and iron.

The interaction between zinc and copper in the pregnant rat was investigated by feeding Sprague-Dawley rats, from mating to term, diets that varied in zinc and copper concentrations. A factorial design was used with diets containing 1, 10, 100 or 1000 micrograms zinc/gram and 0.5, 5, 10 or 100 micrograms copper/gram. Malformations were found only in fetuses from rats fed the zinc-deficient diets (1 microgram/g), and the frequency of malformed fetuses increased as concentration of dietary copper increased. Maternal and fetal tissues of rats fed diets deficient in either zinc or copper were significantly lower in these elements than were those of rats fed a control diet. An antagonistic effect of dietary zinc on maternal and fetal tissue copper concentration was observed. The concentration of fetal liver zinc from rats fed a copper-deficient diet was significantly higher than controls. The concentration of iron in maternal and fetal tissues was significantly affected by the level of dietary zinc, with values highest in the zinc-deficient groups. Maternal plasma cholesterol and triglyceride levels were significantly lower than normal in the zinc-deficient animals. These data show that when the concentration of zinc in the diet is deficient an interaction can occur between dietary zinc and copper such that high levels of copper potentiate the teratogenicity of zinc deficiency.