Intermittent bolus feeding has a greater stimulatory effect on protein synthesis in skeletal muscle than continuous feeding in neonatal pigs.
Orogastric tube feeding, using either continuous or intermittent bolus delivery, is common in infants for whom normal feeding is contraindicated. To compare the impact of different feeding strategies on muscle protein synthesis, after withholding food overnight, neonatal pigs received a complete formula orally as a bolus feed every 4 h or were continuously fed. Protein synthesis rate and translational mechanisms in skeletal muscle were examined after 0, 24, and 25.5 h. Plasma amino acid and insulin concentrations increased minimally and remained constant in continuously fed compared to feed-deprived pigs; however, the pulsatile meal feeding pattern was mimicked in bolus-fed pigs. Muscle protein synthesis was stimulated by feeding and the greatest response occurred after a bolus meal. Bolus but not continuous feeds increased polysome aggregation, the phosphorylation of protein kinase B, tuberous sclerosis complex 2, proline-rich Akt substrate of 40 kDa, eukaryotic initiation factor (eIF) 4E binding protein (4EBP1), and rp S6 kinase and enhanced dissociation of the 4EBP1 ·eIF4E complex and formation of the eIF4E ·eIF4G complex compared to feed deprivation (P < 0.05). Activation of insulin receptor substrate-1, regulatory associated protein of mammalian target of rapamycin, AMP-activated protein kinase, eukaryotic elongation factor 2, and eIF2α phosphorylation were unaffected by either feeding modality. These results suggest that in neonates, intermittent bolus feeding enhances muscle protein synthesis to a greater extent than continuous feeding by eliciting a pulsatile pattern of amino acid- and insulin-induced translation initiation.
USDA/Agriculture Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.
María C
MC
Gazzaneo
Agus
A
Suryawan
Renán A
RA
Orellana
Roberto Murgas
RM
Torrazza
Samer W
SW
El-Kadi
Fiona A
FA
Wilson
Scot R
SR
Kimball
Neeraj
N
Srivastava
Hanh V
HV
Nguyen
Marta L
ML
Fiorotto
Teresa A
TA
Davis
D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000596:Amino Acids / Q000097:blood; D000818:Animals; D000831:Animals, Newborn / Q000235:genetics*; D001786:Blood Glucose / Q000032:analysis; D004032:Diet; D004750:Enteral Nutrition / Q000379:methods; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism; D005260:Female; D007328:Insulin / Q000097:blood; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000502:physiology*; D020652:Peptide Elongation Factor 2 / Q000378:metabolism; D010766:Phosphorylation; D011247:Pregnancy; D014176:Protein Biosynthesis; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
D000596:Amino Acids; D001786:Blood Glucose; D015852:Eukaryotic Initiation Factor-2; D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D009124:Muscle Proteins; D020652:Peptide Elongation Factor 2; D051057:Proto-Oncogene Proteins c-akt; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases