Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/13/2006
Publication Date: 9/1/2006
Citation: Reeves, P.G., Demars, L.C. 2006. Signs of iron deficiency in copper-deficient rats are not affected by iron supplements administered by diet or by injection. Journal of Nutritional Biochemistry. 17:635-642. Interpretive Summary: Iron deficiency is one of the world's most prevalent nutrition problems. The way in which iron is absorbed from the diet is fairly well known; however, there are other factors including other nutrients in the diet that if not in adequate supply will inhibit Fe absorption and the animal becomes iron deficient. One of these nutrients is copper. Recently it was found that a factor called Hephaestin in the intestine aides in iron absorption, but requires copper to do so. If copper is left out of the diet, then iron absorption is reduced. It is also know that bypassing this step in some types of animals by giving copper injections, the animal still becomes iron deficient. This study was performed to determine whether excess iron given by diet or by injections would cure iron deficiency in copper-deficient rats. Male rats were made copper-deficient and then given excess iron by diet or by injecting it into the body. The results showed that iron absorption was reduced by copper deficiency regardless of how the iron was administered, and the rats became iron deficient. However, there is another factor in the blood of animals called ceruloplasmin that is required to keep iron in the correct form in order to get it into immature red cells to make hemoglobin. Ceruloplasmin is also dependent upon copper for activity. In this experiment, ceruloplasmin activity was reduced to almost zero. Thus, the reduction in Hephaestin in the intestine reduced iron absorption, bypassing this step by injecting iron would have no effect on iron deficiency because ceruloplasmin activity was also reduced, preventing hemoglobin synthesis. It is highly likely that in areas of the world where iron deficiency is prevalent, low copper status is also present. If so, the recovery from iron deficiency, during iron supplementation, would be much more efficient if copper status were imporved as well.
Technical Abstract: The goal of this study was to determine the effects of Fe supplementation on anemia of Cu deficieny in rats. In addition, we observed changes in serum and organ Cu and Fe during the development of Cu deficieny. Experiment 1. Weanling male Sprague-Dawley rats were fed AIN-93G diets containing either <0.3 mg Cu (CuD) or 6.0 mg Cu (CuA) per kg diet. Five rats from each group were killed at intervals for the analysis of hematologic parameters and mineral content of various organs. Experiment 2. Two groups of 24 rats each were fed either the CuA diet or the CuD diet for 14 d. Then, three sets of 8 rats in each group received three separate Fe treatments; 1) daily IP injections of 400 ug Fe (Cu-free ferric citrate) per rat for another 14 d; 2) fed similar diets that contained three times the normal amount of Fe (105 mg/kg) for 14 days; or 3) received no further Fe treatment. At d-21, all rats were fed a 1-g meal labeled with 59Fe to determine Fe absorption. After 28 d, rats were killed for the analyses of Fe and Cu status. Results of Experiment 1 showed that within 14 d, CuD rats had lower blood hemoglobin, RBC count, and MCV than CuA rats. Cu concentrations in all tissues measured were lower in the CuD rats than in controls. Serum ceruloplasmin (Cp) activity in CuD rats was only 0.8% of CuA rats at d-7. During this period, enterocyte and liver Fe concentrations were elevated, serum Fe was reduced, but there was no change in spleen Fe. Results of Experiment 2 showed that CuD rats absorbed less Fe than CuA rats. Supplemental Fe by diet or by IP injections did not prevent anemia in the CuD rats or affect other parameters of Cu status. Serum TIBC (transferrin was not changed by Cu deficiency or by Fe supplementation; however, percent transferrin saturation was reduced in CuD rats but was not enhanced by Fe supplementation. These data suggest that anemia of Cu deficiency occurs primarily because of reduced Fe absorption and inefficient loading of Fe into transferrin because of very low Cp activity. This then leads to inefficient delivery of Fe to the erythroid cell for heme and hemoglobin synthesis.