Location: Children's Nutrition Research CenterTitle: Intermittent leucine pulses during continuous feeding alters novel components involved in skeletal muscle growth of neonatal pigs
|MANJARIN, RODRIGO - Children'S Nutrition Research Center (CNRC)|
|BOUTRY-REGARD, CLAIRE - Children'S Nutrition Research Center (CNRC)|
|SURYAWAN, AGUS - Children'S Nutrition Research Center (CNRC)|
|CANOVAS, ANGELA - University Of Guelph|
|PICCOLO, BRIAN - Arkansas Children'S Nutrition Research Center (ACNC)|
|MAJ, MAGDALENA - California Polytechnic State University|
|ABO-ISMAIL, MOHAMMED - California Polytechnic State University|
|NGUYEN, HANH - Children'S Nutrition Research Center (CNRC)|
|FIOROTTO, MARTA - Children'S Nutrition Research Center (CNRC)|
|DAVIS, TERESA - Children'S Nutrition Research Center (CNRC)|
Submitted to: Amino Acids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2020
Publication Date: 9/24/2020
Citation: Manjarin, R., Boutry-Regard, C., Suryawan, A., Canovas, A., Piccolo, B.D., Maj, M., Abo-Ismail, M., Nguyen, H.V., Fiorotto, M.L., Davis, T.A. 2020. Intermittent leucine pulses during continuous feeding alters novel components involved in skeletal muscle growth of neonatal pigs. Amino Acids. 52:1319–1335. https://doi.org/10.1007/s00726-020-02894-5.
Interpretive Summary: Many low-birth-weight infants who have feeding intolerances are fed formula or human milk by gastric tube either continuously at a constant flow rate or intermittently to mimic meal feeding. Researchers at the Children’s Nutrition Research Center in Houston, Texas previously showed using a neonatal piglet model that when neonates are continuously fed formula that is supplemented with leucine, muscle protein synthesis and body weight gain are enhanced. To identify the responsible mechanisms, combined plasma metabolomic analysis with transcriptome expression of the transcriptome and protein catabolic pathways in skeletal muscle were performed. We found evidence to support the hypothesis that the administration of intermittent leucine pulses in continuously orogastric-fed pigs enhances muscle mass gain not only by increasing protein synthetic activity but also by reducing the expression of protein catabolic pathways, as indicated by changes in the transcriptome and metabolome. The novel association between metabolites derived from leucine catabolism and markers of the ubiquitin-proteasome and autophagy-lysosome systems needs to be further studied, as it may help to develop better therapeutic approaches for improving muscle growth in at-risk human infants.
Technical Abstract: When neonatal pigs continuously fed formula are supplemented with leucine pulses, muscle protein synthesis and body weight gain are enhanced. To identify the responsible mechanisms, we combined plasma metabolomic analysis with transcriptome expression of the transcriptome and protein catabolic pathways in skeletal muscle. Piglets (n = 23, 7-day-old) were fed continuously a milk replacement formula via orogastric tube for 21 days with an additional parenteral infusion (800 mu-mol kg-1 h-1) of either leucine (LEU) or alanine (CON) for 1 h every 4 h. Plasma metabolites were measured by liquid chromatography-mass spectrometry. Gene and protein expression analyses of longissimus dorsi muscle were performed by RNA-seq and Western blot, respectively. Compared with CON, LEU pigs had increased plasma levels of leucine-derived metabolites, including 4-methyl-2-oxopentanoate, beta-hydroxyisovalerate, beta-hydroxyisovalerylcarnitine, and 3-methylglutaconate (P < 0.05). Leucine pulses downregulated transcripts enriched in the Kyoto Encyclopedia of Genes and Genomes terms "spliceosome," "GAP junction," "endocytosis," "ECM-receptor interaction," and "DNA replication". Significant correlations were identified between metabolites derived from leucine catabolism and muscle genes involved in protein degradation, transcription and translation, and muscle maintenance and development (P < 0.05). Further, leucine pulses decreased protein expression of autophagic markers and serine/threonine kinase 4, involved in muscle atrophy (P < 0.01). In conclusion, results from our studies support the notion that leucine pulses during continuous enteral feeding enhance muscle mass gain in neonatal pigs by increasing protein synthetic activity and downregulating protein catabolic pathways through concerted responses in the transcriptome and metabolome.