Intermittent Bolus Feeding Has a Greater Stimulatory Effect on Protein Synthesis in Skeletal Muscle than Continuous Feeding in Neonatal Pigs

Abstract

Feeding by orogastric tube, using either continuous or intermittent bolus delivery, is common for infants for whom normal feeding is contraindicated. To determine the impact of different feeding modalities on muscle protein anabolism, neonatal pigs (5–7 day old) received a balanced enteral formula either by intermittent bolus (B, n=7) every four hours or were continuously fed (C, n=5). Fractional protein synthesis rates and translational control mechanisms in skeletal muscle were examined at 0, 24 and 25.5 hours. Plasma amino acid and insulin levels were modestly increased in the continuously fed group and in the bolus group mimicked the pulsatile pattern of meal feeding. Feeding increased protein synthesis by 53% in the continuous group, by 63% in the bolus group before a meal, and by 126 % after a bolus feed. The activation of eukaryotic initiation factor (eIF) 4E binding protein (4EBP1), rp S6 kinase 1 (S6K1), protein kinase B (PKB), dissociation of 4EBP1‐eIF4E complex, and formation of the active eIF4E‐eIF4G complex were unaffected by continuous feeding but were increased more than 10 fold after a bolus meal. These results suggest that intermittent bolus feeding increases muscle protein synthesis to a greater extent than continuous feeding by stimulating translation initiation. (Supported by NIH grants AR‐44474 and AR‐51563 and USDA/ARS 6250510000‐33).Grant Funding Source: NIH grants AR‐44474 and AR‐51563 and USDA/ARS 6250510000‐33