Christos Antipatis

The effects of maternal protein restriction on the growth of the rat fetus and its amino acid supply

Maternal protein deficiency causes fetal growth retardation which has been associated with the programming of adult disease. The growth of the rat fetus was examined when the mothers were fed on diets containing 180, 90 and 60 g protein/kg. The numbers of fetuses were similar in animals fed on the 180 and 90 g protein/kg diets but the number was significantly reduced in the animals fed on the 60 g protein/kg diet. The fetuses carried by the mothers fed on the 90 g protein/kg diet were 7.5% heavier than those of mothers fed on 180 g protein/kg diet on day 19 of gestation, but by day 21 the situation was reversed and the fetuses in the protein-deficient mothers were 14% smaller. Analysis of the free amino acids in the maternal serum showed that on day 19 the diets containing 90 and 60 g protein/kg led to threonine concentrations that were reduced to 46 and 20% of those found in animals fed on the control (180 g/kg) diet. The other essential amino acids were unchanged, except for a small decrease in the branched-chain amino acids in animals fed on the 60 g protein/kg diet. Both low-protein diets significantly increased the concentrations of glutamic acid+glutamine and glycine in the maternal serum. On day 21 the maternal serum threonine levels were still reduced by about one third in the group fed on the 90 g protein/kg diet. Dietary protein content had no effect on serum threonine concentrations in nonpregnant animals. Analysis of the total free amino acids in the fetuses on day 19 showed that feeding the mother on a low-protein diet did not change amino acid concentrations apart from a decrease in threonine concentrations to 45 and 26% of the control values at 90 and 60 g protein/ kg respectively. The results suggest that threonine is of particular importance to the protein-deficient mother and her fetuses. Possible mechanisms for the decrease in free threonine in both mother and fetuses and the consequences of the change in amino acid metabolism are discussed.

Effect of Iron Deficiency on Placental Cytokine Expression and Fetal Growth in the Pregnant Rat

Abstract Iron deficiency anemia is the most common nutritional disorder in the world. Anemia is especially serious during pregnancy, with deleterious consequences for both the mother and her developing fetus. We have developed a model to investigate the mechanisms whereby fetal growth and development are affected by maternal anemia. Weanling rats were fed a control or iron-deficient diet before and throughout pregnancy and were killed at Day 21. Dams on the deficient diet had lower hematocrits, serum iron concentrations, and liver iron levels. Similar results were recorded in the fetus, except that the degree of deficiency was markedly less, indicating compensation by the placenta. No effect was observed on maternal weight or the number and viability of fetuses. The fetuses from iron-deficient dams, however, were smaller than controls, with higher placental:fetal ratios and relatively smaller livers. Iron deficiency increased levels of tumor necrosis factor α (TNFα) only in the trophoblast giant cells of the placenta. In contrast, levels of type 1 TNFα receptor increased significantly in giant cells, labyrinth, cytotrophoblast, and fetal vessels. Leptin levels increased significantly in labyrinth and marginally (P = 0.054) in trophoblast giant cells. No change was observed in leptin receptor levels in any region of the placentas from iron-deficient dams. The data show that iron deficiency not only has direct effects on iron levels and metabolism but also on other regulators of growth and development, such as placental cytokines, and that these changes may, in part at least, explain the deleterious consequences of maternal iron deficiency during pregnancy.

Cytokines and the regulation of apoptosis in reproductive tissues : A Review

PROBLEM: To determine the role of apoptosis‐regulating genes bax and bcl‐2 in reproduction.

Effects of maternal vitamin A status on fetal heart and lung: changes in expression of key developmental genes

Vitamin A is required during pregnancy for fetal lung development. These experiments monitored fetal lung morphology in normal and vitamin A-deficient rats. The expression of elastin and the growth arrest-specific gene 6 ( gas6) in fetal and neonatal hearts and lungs was assessed by Northern blotting. In normal-fed rats, elastin and gas6 were expressed in the fetal lung and heart from day 19 of gestation up to day 2 postnatally. Maternal vitamin A deficiency altered fetal lung development. On day 20, the bronchial passageways were less developed and showed reduced staining for elastic fibers, and in the neonates, the relative air space and the size of the sacculi were reduced. In the fetal lung, the mRNAs for elastin and gas6 were reduced to 56 and 68% of the control values, respectively. In the fetal heart, the mRNA for elastin was reduced to 64% of the control value, whereas gas6 was increased twofold. In the neonate, there was no change in elastin expression in the lung or heart, but gas6 expression in the heart was increased twofold. These results suggest that, in the pregnant rat, vitamin A deficiency may retard fetal lung development or influence the differentiation of critical cell lines. The changes in elastin and gas6 expression may be used to identify the cell types affected.

Moderate maternal vitamin A deficiency affects perinatal organ growth and development in rats.

Vitamin A deficiency during pregnancy is associated with detrimental effects in the offspring. We have developed a rat model to examine specific effects of maternal vitamin A status on perinatal growth and development. A total of 54 female rats were fed a vitamin A-free (VAF), -marginal (VAM) or -sufficient (VAS) diet from weaning until mating (at 7 weeks) and throughout pregnancy. Half of the rats in each group were injected with a single large dose of vitamin A on day 10 of pregnancy. Fetal and neonatal samples were taken on day 20 of pregnancy and the day of birth respectively. Maternal plasma retinol concentrations on day 20 and at birth were 50% and 30% lower in the VAF and VAM when compared to the VAS group. Fetal weight and survival did not differ between groups although placental:fetal ratio was higher in the VAF group than in the VAS group (0.195 (SE 0.005) v. 0.175 (SE 0.004), P < 0.05). Rats fed the VAF diet gave birth at 23.5 d, an average of 1 d later than the other groups, and had lower number of live neonates at birth. Fetal liver, heart and lung weights relative to total body weight were lower in the VAF group and had altered growth trajectories. In neonates, only the relative lung weight was reduced. In addition, an increased protein:DNA ratio indicated hypertrophy in fetal kidneys. Vitamin A injection had no additional effect on length of gestation and fetal or neonatal number. However, injection increased relative fetal organ weights in the VAF group but did not alter the effects of vitamin A deficiency in the neonate. These data suggest that chronic vitamin A deficiency during pregnancy compromises liver, heart and kidney and impairs lung growth and development during the last few days of gestation and reduces number of live neonates at birth.

Vitamin A deficiency during rat pregnancy alters placental TNF-alpha signalling and apoptosis.

PROBLEM: Vitamin A is important for immune function and deficiency is associated with adverse pregnancy outcome. In the rat, vitamin A deficiency reduces both foetal number and neonatal survival. The role of the placenta is uncertain. The effects of maternal vitamin A deficiency on placental cytokines and apoptosis have been investigated.