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Differences in muscle protein synthesis and anabolic signaling in the postabsorptive state and in response to food in 65–80 y old men and women
Author(s) -
Smith Gordon Ian,
Atherton Philip,
Villareal Dennis T.,
Rennie Michael J.,
Mittendorfer Bettina
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.949.4
Subject(s) - anabolism , endocrinology , medicine , phosphorylation , muscle protein , basal (medicine) , sarcopenia , sexual dimorphism , protein kinase b , skeletal muscle , chemistry , biology , insulin , biochemistry
Men have more muscle than women but during aging lose muscle faster than women. To investigate potential mechanisms responsible for this we measured rates of muscle protein synthesis (MPS) with stable isotope‐labeled tracer techniques and the phosphorylation status of anabolic signaling elements during postabsorptive conditions and feeding in men (n=13) and women (n=16) who were matched on age (65–80 y) and body mass index. Postabsorptive MPS was ∼25% less in men than in women (0.045 [0.039; 0.057] vs 0.058 [0.052; 0.072]; %·h −1 ; medians [quartiles]; P =0.02) and feeding increased MPS in men (to 0.071 [0.059; 0.079] %·h −1 ; P <0.01) but not women (0.060 [0.056; 0.089] %·h −1 ). Postabsorptively, muscle phosphorylated Akt Ser473 , p70s6k Thr389 , eIF4E Ser209 and eIF4E‐BP1 Thr37/46 concentrations were not different between sexes but that of eEF Thr56 was less in women, consonant with more activated protein elongation. Accordingly, feeding increased eIF4E Ser209 and eIF4E‐BP1 Thr37/46 phosphorylation in men (both P <0.05) but not in women. Thus, there is sexual dimorphism in MPS and its control in older adults with a diminished basal rate of MPS, which operates over much of the day, potentially explaining the faster loss of muscle in older men. This research was supported by grants from the US NIH, the University of Nottingham, the UK BBSRC, and the European Union.