Excess Dietary Zinc for the Maternal Rat, and Zinc, Iron, Copper, Calcium, and Magnesium Content and Enzyme Activity in Maternal and Fetal Tissues

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Abstract
Excess dietary zinc (0.4%) was fed to the maternal rat during gestation to study its effect on the content of zinc, copper, iron, calcium and magnesium and the activity of various enzymes in maternal and fetal tissues. Succinic dehydrogenase activity was not altered in maternal and fetal liver and heart during gestation. Cytochrome oxidase activity was reduced in fetal liver, but not heart, and maternal liver and heart at day 16 of fetal age only. Xanthine oxidase activity was undetected in fetal liver and heart at day 22, irrespective of treatment. Activity of xanthine oxidase was lower in maternal heart, but not liver, at day 22. Ceruloplasmin activity was undetected in maternal serum at day 22. Changes in mineral content of fetal liver and body and maternal liver, heart, adrenals, kidneys, spleen, gastrocnemius muscle, thymus, and brain at day 22 of fetal age are as follows. Zinc was increased and copper was reduced in fetal body and liver. Iron was lower in the body, but unchanged in the liver. Total calcium and concentration of calcium were higher in fetal liver, but were lower in the body. Magnesium concentration, but not total, was elevated in liver and body. Total zinc and concentration of zinc were elevated in maternal liver, kidneys, and brain and total zinc was higher in thymus. Zinc content was unaltered in the other tissues. Copper was reduced in the liver only. No change was found in iron content of the tissues. Total calcium and concentration of calcium were higher in heart and brain, but reduced in kidneys. No change in calcium content was noted in the other tissues. Total magnesium and concentration of magnesium were lower in spleen; magnesium concentration was reduced in kidneys. The other tissues had no change in magnesium. The changes found in zinc and calcium in the maternal brain suggest further work in the area of brain metabolism and performance. The relation of reduced serum ceruloplasmin to iron metabolism in the maternal and fetal animal on an excess zinc regimen is discussed.