Intermittent Bolus Feeding Enhances Lean Tissue Accretion by Increasing Muscle Amino Acid Transport and Protein Turnover Compared with Continuous Feeding in Neonates (original) (raw)

The FASEB Journal, 2013

Abstract

Orogastric tube feeding is recommended in neonates unable to ingest food normally, and can be administered by intermittent bolus (INT) or continuous (CON) infusion. Recently, we showed that INT compared to CON feeding enhances lean tissue accretion by increasing muscle protein synthesis in neonates. To determine the mechanism for this response, neonatal pigs (n=6, 6‐d‐old) were fed the same diet in equivalent amounts continuously or intermittently (meal every 4h) for 21d. Insulin receptor and insulin receptor substrate 1 expression and protein kinase B phosphorylation in skeletal muscle were unaffected by feeding modality. Formation of the active eukaryotic initiation factor (eIF) 4E‐eIF4G complex and phosphorylation of ribosomal protein S6 kinase were higher and phosphorylation of eIF2α was lower in INT compared to CON fed pigs indicating increased translation initiation (P<0.05). Sodium‐coupled neutral amino acid transporter 2, but not L‐type amino acid transporter 1, expression was higher in INT compared to CON pigs suggesting enhanced glutamine transport (P<0.05). Abundance of the ubiquitin ligases, muscle RING finger‐1 and F‐box protein atrogin‐1/MAFbx, was higher for INT compared to CON pigs (P<0.05). These results suggest that intermittent feeding enhances lean tissue accretion by increasing amino acid transport and protein turnover. (Supported by NIH AR444474 and USDA/ARS 6250–51000‐055)

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