Iron and Zinc Concentrations and 59Fe Retention in Developing Fetuses of Zinc-Deficient Rats

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Because disturbances in iron metabolism might contribute to the teratogenicity of zinc deficiency, we examined the effect of zinc deficiency on fetal iron accumulation and maternal and fetal retention of 59Fe. Pregnant rats were fed from mating a purified diet containing 0.5, 4.5 or 100 µg Zn/g. Laparotomies were performed on d 12, 16, 19 and 21 of gestation. Maternal blood and concepti were analyzed for zinc and iron. Additional groups of dams fed 0.5 or 100 µg Zn/g diet were gavaged on d 19 with a diet containing 59Fe. Six hours later maternal blood and tissues, fetuses and placentas were counted for 59Fe. Maternal plasma zinc, but not iron, concentration was affected by zinc deficiency on d 12. Embryo zinc concentration on d 12 increased with increasing maternal dietary zinc, whereas iron concentration was not different among groups. On d 16–21 plasma iron was higher in dams fed 0.5 µg Zn/g diet than in those fed 4.5 or 100 µg/g, whereas plasma zinc was lower in dams fed 0.5 or 4.5 µg Zn/g than in those fed 100 µg Zn/g diet. On d 19 zinc concentration in fetuses from dams fed 0.5 µg/g zinc was not different from that of those fed 4.5 µg/g zinc, and iron concentration was higher in the 0.5 µg Zn/g diet group. The increase in iron concentration in zinc-deficient fetuses thus occurs too late to be involved in major structural teratogenesis. Although whole blood concentration of 59Fe was not different in zinc-deficient and control dams, zinc-deficient dams had more 59Fe in the plasma fraction. Retention of 59Fe in maternal tissues and litters was not different in zinc-deficient and control groups, but 59Fe/g body weight in zinc-deficient fetuses was 170% of that in control rats. Analysis of zinc, iron and copper distribution by gel filtration chromatography showed that the increase in tissue iron was in the ferritin-hemosiderin peak in maternal and fetal liver and placenta.