Iron homeostasis during pregnancy

Developmental iron deficiency anemia (IDA) causes brain and behavioral deficits in rodent models, which cannot be reversed when treated at periods equivalent to later infancy in humans This study sought to determine whether earlier iron treatment can normalize deficits of IDA in rats and what iron dose is optimal The offspring of dams with IDA during gestation were cross-fostered at postnatal d (P) 8 to dams receiving diets with 1 of 3 iron concentrations until weaning (P21): 0003-001 g/kg [totally iron deficient (TID)]; 004 g/kg [formerly iron deficient (FID-40)]; or 04 g/kg (FID-400) Always iron-sufficient control dams (CN-40) received a 004-g/kg iron diet At P21, TID pups received a 001 g iron/kg diet; all others received a 004 g iron/kg diet Hematocrit and brain iron and monoamine concentrations were assessed at P21 and P100 Pup growth, development, activity, object recognition, hesitancy, and watermaze performance were evaluated Regional brain iron was restored by iron treatment Regional monoamine and metabolite concentrations were elevated in FID-40 rats and reduced in FID-400 and TID rats compared with CN-40 rats FID-40 offspring had motor delays similar to TID during lactation and FID-400 rats had elevated thigmotaxis similar to TID rats at P25 and P100 in the spatial watermaze In conclusion, iron treatment at P8 in rats did not normalize all monoamine or behavioral measures after early IDA Moderate iron treatment improved adult behavior, but higher iron treatment caused brain and behavioral patterns similar to TID in the short and long term

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Behavior and Monoamine Deficits in Prenatal and Perinatal Iron Deficiency Are Not Corrected by Early Postnatal Moderate-Iron or High-Iron Diets in Rats

A retrospective study on the effect of intensive nutrition counseling on weight gain of pregnant women and birth weight of their infants was conducted at an outpatient clinic by comparing one group of 86 women who attended only a nutrition class with another group of 114 women who attended the class plus multiple counseling sessions on appropriate weight gain and nutrient intake. The women receiving the counseling on an average gained 2.5 kg more weight, had fewer low-birth-weight infants (4% vs. 13%), and had infants weighing 100 gm more at birth. That indicates that intensive nutrition counseling results in a superior outcome of pregnancy. When the cost of intensive neonatal care for six infants was compared with the cost of nutrition counseling, a benefit-to-cost ratio of 1:5 was found.

Efficacy of prenatal nutrition counseling: weight gain, infant birth weight, and cost-effectiveness.

In addition to its role in the activity of specialized proteins such as hemoglobin and myoglobin, iron is required as a cofactor in several important enzymes common to most animal cells. One such enzyme, ribonucleotide reductase, which regulates the production of deoxyribonucleotides during DNA synthesis, requires a continuous supply of iron to maintain its activity throughout the process of DNA replication. The mechanism by which animal cells normally acquire iron involves receptor-mediated uptake of iron-loaded transferrin, followed by release of apotransferrin. The density of transferrin receptors on the cell surface is greatly increased in rapidly dividing normal and neoplastic cells. Various mitogens and certain organogenic tissue interactions have been shown to induce the appearance of transferrin receptors, signalling the onset of DNA replication. Interference with this process of iron delivery causes the rapid arrest of cell cycling, frequently during the S phase itself, which underscores the importance of iron for DNA replication. Although most circulating transferrin is synthesized in the liver and embryonic yolk sac, smaller quantities are produced in several other embryonic organs and certain other adult tissues. It has been suggested that local synthesis and/or release of transferrin supplies the iron required by rapidly growing cells in situations where the cells do not have ready access to adequate amounts of plasma transferrin due to incomplete development of the vasculature or the presence of blood-tissue barriers (Ekblom and Thesleff, 1985; Meek and Adamson, 1985). Oligodendrocytes and Schwann cells have been shown to synthesize and/or contain high concentrations of transferrin and these cells therefore may constitute a local source of this factor for neurons, whose growth and survival in vitro require transferrin. Transferrin in central and peripheral nervous tissues may be significant for the trophic or growth-promoting effect neurons exert on cells of certain tissues. Transferrin duplicates the activity of neural tissue or neural extracts on growth and development of cultured skeletal myoblasts from chick embryos and on proliferation of mesenchymal cells in blastemas from regenerating amphibian limbs, two systems that have been widely used in investigations of the growth-promoting influence of nerves. Moreover, removal of active transferrin from neural extracts, either with antibodies to transferrin or chelation of the iron, inhibits reversibly the effect of the extract in these developing systems. While the physiological significance of the extract in these developing systems.(ABSTRACT TRUNCATED AT 400 WORDS)

Transferrin and the Growth-Promoting Effect of Nerves

Vitamin B6 nutritional status of a group of female adolescents.

The effects of feeding four levels of dietary iron, 10, 50, 250 and 1.250 mg/kg were studied during pregnancy in growing and adult rats. Hematological measurements, plasma iron and total iron binding capacity, and iron content in liver, spleen and tibia were compared relative to pregnancy, diet and growth. Iron content in fetuses and fetal livers were compared relative to diet and growth of the dams. All parameters were lowest in rats fed the 10 mg Fe/kg diet. The highest level of iron fed, 1,250 mg/kg, resulted in increased iron content in liver, spleen and tibia of all treatment groups but did not alter hematological values or fetal iron content. Pregnant rats fed any of the four levels of iron had significantly lower Hb, Ht, total and storage iron concentration and ferritin and hemosiderin iron in liver than nonpregnant rats fed the same levels. The level of dietary iron needed by growing pregnant rats for maximal iron content in fetuses and fetal livers was between 50 and 250 mg Fe/kg which was fivefold that needed to obtain maximal hemoglobin concentration in dams. However, adult pregnant rats only needed between 10 to 50 mg Fe/kg for both maximal iron stores in fetal tissues and maximal hemoglobin concentration.

Effects of Different Levels of Dietary Iron on Pregnancy Superimposed upon Growth in the Rat

Effects of pregnancy superimposed upon a rapid phase of growth in the rat on the vitamin B-6 needs during gestation were examined Rats were fed 12, 24, 48, 96, or 192 mg pyridoxine-HCl/kg diet from weaning Some animals from each dietary treatment were mated at 55 (P-55) and 115 (P-115) days of age; others of the same ages served as nonpregnant controls Analyses were made on day 21 of gestation Excepting the 12-mg diet treatment, maternal weight gains during gestation were greater for P-55 groups compared with gains of the P-115 groups, possibly reflecting maternal growth Both maternal weight gains and fetal weights were less for the 12-mg, P-55 group; otherwise reproductive performance was similar among the groups On the basis of stimulation of erythrocyte alanine aminotransferase activity by pyridoxal phosphate added in vitro, the needs in all pregnant and nonpregnant groups were met by 24 mg pyridoxine/kg diet However, on the basis of vitamin B-6 saturation of tissues, the pyridoxine needs were 96 mg/kg diet for young growing animals and 48 mg/kg diet for older animals in which growth had almost ceased The needs for both young and older pregnant animals possibly exceeded 192 mg pyridoxine/kg diet for vitamin B-6 saturation of maternal liver, fetus, and fetal brain Pregnancy superimposed upon a rapid phase of growth in conjunction with a restricted intake of pyridoxine resulted in low values for most parameters used in the assessments compared with values for animals fed the same vitamin level but mated after growth velocity had diminished

Wen-Ju Lin

Papers

Effects of Different Levels of Dietary Iron on Pregnancy Superimposed upon Growth in the Rat

Effects of Different Levels of Pyridoxine Fed during Pregnancy Superimposed upon Growth in the Rat