Pulsatile Leucine Administration during Continuous Enteral Feeding Enhances Skeletal Muscle Mechanistic Target of Rapamycin Complex 1 Signaling and Protein Synthesis in a Preterm Piglet Model.
J Nutr
; 154(2): 505-515, 2024 02.
Article
em En
| MEDLINE
| ID: mdl-38141773
ABSTRACT
BACKGROUND:
Continuous feeding does not elicit an optimal anabolic response in skeletal muscle but is required for some preterm infants. We reported previously that intermittent intravenous pulses of leucine (Leu; 800 µmol Leu·kg-1·h-1 every 4 h) to continuously fed pigs born at term promoted mechanistic target of rapamycin complex 1 (mTORC1) activation and protein synthesis in skeletal muscle.OBJECTIVES:
The aim was to determine the extent to which intravenous Leu pulses activate mTORC1 and enhance protein synthesis in the skeletal muscle of continuously fed pigs born preterm.METHODS:
Pigs delivered 10 d preterm was advanced to full oral feeding >4 d and then assigned to 1 of the following 4 treatments for 28 h 1) ALA (continuous feeding; pulsed with 800 µmol alanine·kg-1·h-1 every 4 h; n = 8); 2) L1× (continuous feeding; pulsed with 800 µmol Leu·kg-1·h-1 every 4 h; n = 7); 3) L2× (continuous feeding; pulsed with 1600 µmol Leu·kg-1·h-1 every 4 h; n = 8); and 4) INT (intermittent feeding every 4 h; supplied with 800 µmol alanine·kg-1 per feeding; n = 7). Muscle protein synthesis rates were determined with L-[2H5-ring]Phenylalanine. The activation of insulin, amino acid, and translation initiation signaling pathways were assessed by Western blot.RESULTS:
Peak plasma Leu concentrations were 134% and 420% greater in the L2× compared to the L1× and ALA groups, respectively (P < 0.01). Protein synthesis was greater in the L2× than in the ALA and L1× groups in both the longissimus dorsi and gastrocnemius muscles (P < 0.05) but not different from the INT group (P > 0.10). Amino acid signaling upstream and translation initiation signaling downstream of mTORC1 largely corresponded to the differences in protein synthesis.CONCLUSIONS:
Intravenous Leu pulses potentiate mTORC1 activity and protein synthesis in the skeletal muscles of continuously fed preterm pigs, but the amount required is greater than in pigs born at term.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Recém-Nascido Prematuro
/
Nutrição Enteral
Limite:
Animals
/
Humans
/
Newborn
Idioma:
En
Revista:
J Nutr
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
Estados Unidos