EFFECTS OF PRENATAL EXPOSURE TO LOW AND HIGH DIETARY PROTEIN LEVELS ON MATERNAL AND FETAL AMINO ACID METABOLISM IN RATS.

EFFECTS OF PRENATAL EXPOSURE TO LOW AND HIGH DIETARY PROTEIN

LEVELS ON MATERNAL AND FETAL AMINO ACID METABOLISM IN RATS.

Maren Daenzer

, Jeanette Günther

, Klaus J. Petzke

, Cornelia C.

Metges

, Susanne Klaus

1

German Institute of Human Nutrition in Potsdam; Bergholz-Rehbrücke, Germany;

2

Research Institute for the Biology of

2

Farm Animals, Dummerstorf, Germany

Introduction: There is increasing evidence that nutritional programming during fetal development might be involved in the world wide increasing obesity epidemic. In the rat model it has been shown that nutritional programming by low maternal protein intake during gestation results in intra-uterine growth restriction and subsequent development of metabolic disturbances in adult life such as hypertension and insulin resistance. There is some epidemiological evidence that high protein intake during early development might also influence later adiposity, but so far there is little direct experimental evidence. We have shown that a high (40%) protein intake of rats during gestation resulted in a decreased birth weight, a fast catch up growth during suckling period, and increased adiposity and decreased energy expenditure at 8 weeks of age compared to the adequate (20%) protein (Daenzer et al., J Nutr. 132: 142-144, 2002).

Methods We investigated parameters of protein metabolism of pregnant dams and their fetuses during feeding of different protein diets. Rats were time-mated and fed isocaloric diets containing low (LP, 10% w/w), adequate (AP, 20%) or high protein (HP, 40%) concentrations. Plasma amino acid (aa) concentrations during gestation were measured by HPLC. Additionally we studied the incorporation of orally applied

C-labelled lysine (lys) and leucine (leu) into maternal plasma, fetal, and placental protein.

Results Placental and fetal weights were not different in LP, NP or HP on gestation day 14 and 19. Urea in maternal plasma was highest in HP at all time points, indicating an increased aa oxidation. Maternal plasma concentrations of branched chain aa were also highest in HP. Interestingly, taurine concentrations were increased during gestation in LP and AP, but not in HP. Incorporation of

C-lys and

C-leu into maternal plasma protein was decreased with increasing protein intake (LP>NP>HP). Incorporation of

C-leu and

13

C-lys into both placental and fetal protein was decreased in HP compared to AP or LP.

Conclusions: These results are indicative of higher oxidation of dietary aa after HP feeding with the consequence of lower aa availability for fetal or placental protein synthesis. We conclude that feeding HP diets during pregnancy might have consequences for fetal development, especially during time of rapid tissue growth at gestation days 19- 22.

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