Intermittent Bolus Feeding Increases Visceral Tissue Protein Synthesis More Than Continuous Feeding in Neonatal Pigs

Abstract

Orogastric tube feeding, using either continuous or intermittent bolus delivery, is commonly used in infants unable to feed orally. To compare the impact of different feeding strategies on visceral tissue protein synthesis, neonatal pigs (5–7 day old) received a balanced formula orally either by intermittent bolus every 4 h (n=13) or continuously (n=9), or they were overnight fasted (n=6). Fractional protein synthesis and translational mechanisms in visceral tissues were examined at 0, 24, and 25.5 h. Plasma amino acid and insulin levels modestly increased in the continously fed group, whereas in the bolus meal group the pulsatile meal feeding pattern was mimicked. Compared to fasting, protein synthesis in the liver, pancreas, jejunum, and kidney increased in response to feeding in bolus and continuously fed pigs (P< 0.05), but the greatest increase occurred after a bolus meal (P< 0.001). Bolus meals, but not continuous feeds, increased the activation of eukaryotic initiation factor (eIF) 4E binding protein (4EBP1) and rp S6 kinase 1 (S6K1) (P< 0.05). Eukariotic elongation factor 2 (eEF2) and eIF2α phosphorylation were unaffected by both feeding modalities. These results suggest that intermittent bolus feeding increases protein synthesis in visceral tissues to a greater extent than continuous feeding by stimulating translation initiation. (Supported by NIH AR-44474 and AR-51563 and USDA/ARS 6250-51000-055).