The biphasic nature of protein metabolism during pregnancy in the rat

Naismith, D. J.; Morgan, B. L.

doi:10.1079/bjn19760109

Cited by 91 publications

(40 citation statements)

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“…wk of pregnancy. During this anabolic phase of gestation, the protein increments in fetuses are insignificant, whereas the dam builds up a reserve of proteins (38). Conversely, the last days of pregnancy, during which fetal effects of maternal protein deprivation become apparent, correspond to a period of rapid fetal growth and utilization of the maternal protein reserve (38).…”

Section: Discussionmentioning

confidence: 99%

“…During this anabolic phase of gestation, the protein increments in fetuses are insignificant, whereas the dam builds up a reserve of proteins (38). Conversely, the last days of pregnancy, during which fetal effects of maternal protein deprivation become apparent, correspond to a period of rapid fetal growth and utilization of the maternal protein reserve (38). The increase in food intake in pregnant rats fed the low protein diet ad libitum on d 0-17 and the reduction during the last 5 d (18-22 d) has been reported previously (39).…”

Section: Discussionmentioning

confidence: 99%

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Effects of Maternal Protein Malnutrition on Fetal Growth, Plasma Insulin-like Growth Factors, Insulin-like Growth Factor Binding Proteins, and Liver Insulin-like Growth Factor Gene Expression in the Rat

Muaku¹,

Beauloye²,

Thissen³

et al. 1995

Pediatr Res

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/We examined the effects of maternal dietary protein restriction on fetal growth and expression of IGF-I and -11, and ' IGF-binding proteins (IGFBP). We sought to dissociate the , respective effects of maternal protein versus calorie restriction on growth indices and IGF synthesis by the neonates of proteinrestricted dams. Pregnant Wistar rats (six to eight per group) fed a low (5%) protein diet throughout gestation had impaired body weight gain compared with controls fed a normal (20%) protein diet (by 45%, p < 0.001). Their serum and liver IGF-I concentrations and liver IGF-I mRNA concentrations were also reduced by 60, 80, and 50%, respectively. Serum IGFBP-3 was reduced by 60% in protein-restricted dams within 1 to 2 h after delivery ( p < 0.001 versus controls), although IGFBP-1, -2, and -4 were not significantly affected by the dietary protein intake. In pups of ' protein-restricted dams, the mean body and liver weight at birth was 15-20% less than that observed in the progeny from normal protein-fed dams ( p < 0.01). Their plasma and liver IGF-I concentrations were 30 and 60% lower, respectively, whereas, liver IGF-I mRNA abundance was reduced by 50% ( p < 0.01).In contrast, neonatal plasma IGF-I1 and liver IGF-I1 mRNA concentrations wen: not significantly affected by the maternal protein malnutrition. Also, the plasma levels of IGFBP were not altered in the growlh-retarded pups. There is also evidence that the IGF may regulate fetal growth and differentiation. IGF and their mRNA are present in most fetal tissues (2-4); specific IGF receptors and IGFBP are widely expressed during fetal life (5); and IGF exert mitogenic

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effects of Maternal Protein Malnutrition on Fetal Growth, Plasma Insulin-like Growth Factors, Insulin-like Growth Factor Binding Proteins, and Liver Insulin-like Growth Factor Gene Expression in the Rat

Muaku¹,

Beauloye²,

Thissen³

et al. 1995

Pediatr Res

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“…In the rat, there are two separate phases of protein metabolism during pregnancy [1]. During the first two weeks * Corresponding author: wdr@rri.sari.ac.uk in the anabolic phase, the dam builds up a reserve of protein, particularly in the liver.…”

Section: Introductionmentioning

confidence: 99%

The effect of dietary protein on the amino acid supply and threonine metabolism in the pregnant rat

Rees¹,

Hay²,

Antipatis³

2006

Reprod. Nutr. Dev.

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-To characterise the effects of dietary protein content on threonine metabolism during pregnancy, rats were fed diets containing 18% or 9% protein and then killed at different stages of gestation. Serum threonine concentrations fell significantly faster in the animals fed the diet containing 9% protein when compared to those fed the diet containing 18% protein. On day 4 of gestation the rate of threonine oxidation was higher in maternal liver homogenates prepared from the animals fed the diet containing 18% protein. The rate of threonine oxidation by liver homogenates fell as gestation proceeded in both diet groups. The activity of threonine dehydrogenase in the maternal liver was unaffected by dietary protein content at all stages of gestation. Serine-threonine dehydratase activity in homogenates of the maternal liver was transiently increased during the early stages of gestation in the animals fed high protein diets but was unchanged in the low protein groups. There was an increase in serine-threonine dehydratase activity in the kidney during the later stages of gestation but this was unaffected by the protein content of the maternal diet. These data show that the changes in free threonine concentrations cannot be accounted for through changes in the oxidation rate and suggest that some other factor influences the unusual metabolism of this amino acid during gestation. threonine dehydratase / threonine dehydrogenase / protein metabolism / pregnancy / foetus / metabolic programming Abbreviations: SDH, serine/threonine dehydratase; TDH, threonine dehydrogenase; PCA, perchloric acid; TCA, trichloroacetic acid.

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“…This 'catabolic phase' occurs irrespective of the protein intake of the mother, indicating that it is under hormonal rather than dietary control. Experiments in which a protein supplement was given to malnourished rat dams, for 5 d only, in early pregnancy showed convincingly that the protein store is transferred to the uterus, promoting an increase in cellularity and protein content of the foetuses (Naismith & Morgan, 1976). (Table 4. ) In human subjects the measurement of N-balance is one of the few procedures available for the study of that dietary protein would ever be a factor limiting milk volume.…”

Section: Fig 2 Changes In Activity Ofmentioning

confidence: 99%