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Title: Age-dependent capacity to accelerate protein synthesis dictates the extent of compensatory growth in skeletal muscle following undernutrition

Author
item FIOROTTO, MARTA - Children'S Nutrition Research Center (CNRC)
item DAVIS, TERESA - Children'S Nutrition Research Center (CNRC)
item SOSA, HORACIO - Children'S Nutrition Research Center (CNRC)
item ESTRADA, IRMA - Children'S Nutrition Research Center (CNRC)
item WATSON, KERI - Children'S Nutrition Research Center (CNRC)
item KARHSON, DEBRA - Children'S Nutrition Research Center (CNRC)

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2010
Publication Date: 4/24/2010
Citation: Fiorotto, M.L., Davis, T.A., Sosa, H.A., Estrada, I.J., Watson, K.L., Karhson, D. 2010. Age-dependent capacity to accelerate protein synthesis dictates the extent of compensatory growth in skeletal muscle following undernutrition [abstract]. Federation of American Societies for Experimental Biology Conference, Session: Regulation of protein synthesis and breakdown by nutrients, exercise, and aging, April 24-28, 2010, Anaheim, California. Vol 24: Abstract No. 97.8.

Interpretive Summary:

Technical Abstract: In both humans and animals, impaired growth during early life compromises adult lean body mass and muscle strength despite skeletal muscle’s large regenerative capacity. To identify the significance of developmental age on skeletal muscle’s capacity for catch-up growth following an episode of under nutrition, mice were suckled on control dams fed a 20% protein diet, or from birth to 11 (early malnutrition, EM), or 11 to 22 (late malnutrition, LM) days of age on dams fed a low-protein (8%) diet. They were re-fed by cross-fostering (EM) to control dams, or weaning (LM) to a control (20% protein) diet. Hindlimb muscle mass and fractional protein synthesis rates (FSR) were measured on days 0, 2, 7 and 21 of refeeding (n=7–9 per age per treatment). On day 0, EM and LM muscles weighed 76% and 84% of age-matched control values, respectively (P<0.001). After 21 d of refeeding, muscles weighed 94% (EM; NS) and 88% (LM; P<0.001) of control values. FSR were significantly higher in EM than control muscles 2 and 7 d after refeeding (P<0.01), whereas in LM pups, values were similar to controls at all ages. The increase in FSR in EM pups upon refeeding was attributable to increased ribosomal abundance. The data suggest that skeletal muscle’s ability to effect catch-up growth is dictated by a developmental stage-dependent capacity for ribosome biogenesis.