Leucine Pulse Increases Skeletal Muscle Protein Synthesis during Continuous Feeding in Neonatal Pigs

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Continuous orogastric tube feeding is used for infants unable to maintain an oral diet. Orogastric bolus feeding has a greater stimulatory effect on muscle protein synthesis than continuous feeding in neonatal pigs. Leucine administration stimulates protein synthesis, but its effects during continuous feeding have not been investigated. Twenty piglets (8‐d‐old) received formula for 24h continuously (CON) or by bolus (BOL), i.e., every 4h for 15min. For the CON+LEU group, leucine was administered parenterally (800μmol•kg−1•h−1) every 4h for 1h. The leucine pulse increased circulating leucine (P<0.0005), but had no effect on isoleucine and valine concentrations. Circulating insulin, glucose, and most other essential amino acids increased 15min after the BOL meal (P<0.05) and returned to baseline by 2h, but were unchanged in CON and CON+LEU groups. Protein synthesis rates in longissimus dorsi, gastrocnemius and soleus muscles were greater in the CON+LEU and BOL than in the CON group (P<0.005). In the BOL and CON+LEU groups, there was an increase in the phosphorylation of ribosomal protein S6 kinase 1 and the formation of active eIF4E.eIF4G complex in skeletal muscle (P<0.05). In conclusion, administration of a leucine pulse during continuous orogastric feeding increases skeletal muscle protein synthesis in neonatal pigs by stimulating translation initiation (NIH AR444474 and USDA/ARS 6250‐51000‐055).Grant Funding Source: NIH‐USDA/ARS