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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