Location: Children's Nutrition Research CenterTitle: Impact of prolonged leucine supplementation on protein synthesis and lean growth in neonatal pigs
|COLUMBUS, DANIEL - Children'S Nutrition Research Center (CNRC)|
|STEINHOFF-WAGNER, JULIA - Children'S Nutrition Research Center (CNRC)|
|SURYAWAN, AGUS - Children'S Nutrition Research Center (CNRC)|
|NGUYEN, HANH - Children'S Nutrition Research Center (CNRC)|
|HERNANDEZ-GARCIA, ADRIANA - Children'S Nutrition Research Center (CNRC)|
|FIOROTTO, MARTA - Children'S Nutrition Research Center (CNRC)|
|DAVIS, TERESA - Children'S Nutrition Research Center (CNRC)|
Submitted to: American Journal of Physiology - Endocrinology and Metabolism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2015
Publication Date: 9/15/2015
Citation: Columbus, D.A., Steinhoff-Wagner, J., Suryawan, A., Nguyen, H.V., Hernandez-Garcia, A., Fiorotto, M.L., Davis, T.A. 2015. Impact of prolonged leucine supplementation on protein synthesis and lean growth in neonatal pigs. American Journal of Physiology - Endocrinology and Metabolism. 309(6):601-610.
Interpretive Summary: Almost 8% of infants who are born in the U.S. are born of a low birth weight. Most of these infants are small when they are discharged from the hospital and are at increased risk for obesity and diabetes when they are older. Therefore, optimizing their nutritional management is crucial for achievement of their immediate and long-term health and well-being. Using the neonatal pig as a model for the human infant, we showed that supplementation of a standard milk-based formula with the essential amino acid, leucine, can modestly increase weight gain and lean body mass of newborns. This effect was due to the increase in the synthesis of proteins within their muscles. The study suggests that supplementation with leucine has the potential to improve the growth of lean tissue in the newborn.
Technical Abstract: Most low-birth weight infants experience extrauterine growth failure due to reduced nutrient intake as a result of feeding intolerance. The objective of this study was to determine whether prolonged enteral leucine supplementation improves lean growth in neonatal pigs fed a restricted protein diet. Neonatal pigs (n = 14-16/diet, 5 days old, 1.8 +/- 0.3 kg) were fed by gastric catheter a whey-based milk replacement diet with either a high protein (HP) or restricted protein (RP) content or RP supplemented with leucine to the same level as in the HP diet (RPL). Pigs were fed 40 ml/kg body wt(-1)meal(-1) every 4 h for 21 days. Feeding the HP diet resulted in greater total body weight and lean body mass compared with RP-fed pigs (P < 0.05). Masses of the longissimus dorsi muscle, heart, and kidneys were greater in the HP- than RP-fed pigs (P < 0.05). Body weight, lean body mass, and masses of the longissimus dorsi, heart, and kidneys in pigs fed the RPL diet were intermediate to RP- and HP-fed pigs. Protein synthesis and mTOR signaling were increased in all muscles with feeding (P < 0.05); leucine supplementation increased mTOR signaling and protein synthesis rate in the longissimus dorsi (P < 0.05). There was no effect of diet on indices of protein degradation signaling in any tissue (P > 0.05). Thus, when protein intake is chronically restricted, the capacity for leucine supplementation to enhance muscle protein accretion in neonatal pigs that are meal-fed milk protein-based diets is limited.