Nonnutritive
Factors in Colostrum Enhance Myofibrillar Protein Synthesis in the
Newborn Pig
MARTA L. FIOROTTO,
TERESA A. DAVIS, PETER J. REEDS and DOUGLAS G. BURRIN
USDA/ARS Children¡¯s Nutrition Research Center, Department of Pediatrics,
Baylor College of Medicine, Houston, Texas 77030, U.S.A.
Correspondence and reprint requests: Marta L. Fiorotto, Ph.D., CNRC,
Department of Pediatrics, 1100 Bates St., Houston, TX 77030, U.S.A.
Colostrum is a complex source of nutrients, immune factors, and bioactive
substances consumed by newborn mammals. In previous work, we observed
that protein synthesis in the skeletal muscle of newborn piglets is
enhanced when they are fed colostrum rather than a nutrient-matched
formula devoid of growth factors. To elucidate the mechanisms responsible
for this response, we contrasted the fractional rates of sarcoplasmic
and myofibrillar protein synthesis of newborn piglets that received
only water with those fed for 24 h with colostrum, a nutrient-matched
formula, or mature sow¡¯s milk. Compared with water, feeding resulted
in a 2.5- to 3-fold increase in total skeletal muscle protein synthesis,
and this increase was 28% greater in the colostrum-fed than either
the formula- or mature milk-fed piglets. Feeding also stimulated muscle
ribosome and total polyadenylated RNA accretion. Ribosomal translational
efficiency, however, was similar across all fed groups. The greater
stimulation of protein synthesis in colostrum-fed pigs was restricted
entirely to the myofibrillar protein compartment and was associated
with higher ribosome and myosin heavy chain mRNA abundance. Taken
together, these data suggest that nonnutritive factors in colostrum
enhance ribosomal accretion and muscle-specific gene transcription
that, in turn, stimulate specifically the synthesis of myofibrillar
proteins in the skeletal musculature of the newborn.
Abbreviations:
FSR, fractional synthesis rate
MHC, myosin heavy chain
GAPDH, glyceraldehyde phosphate dehydrogenase
polyA, polyadenylated RNA
rRNA, ribosomal RNA
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