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Muscle Fn14 gene expression is associated with fat‐free mass retention during energy deficit at high altitude

Pasiakos, Stefan M. ; Berryman, Claire E. ; Carbone, John W. ; Murphy, Nancy E. ; Carrigan, Christopher T. ; Bamman, Marcas M. ; Ferrando, Arny A. ; Young, Andrew J. ; Margolis, Lee M.

Physiological Reports, July 2018, Vol.6(14), pp.n/a-n/a [Rivista Peer Reviewed]

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  • Titolo:
    Muscle Fn14 gene expression is associated with fat‐free mass retention during energy deficit at high altitude
  • Autore: Pasiakos, Stefan M. ; Berryman, Claire E. ; Carbone, John W. ; Murphy, Nancy E. ; Carrigan, Christopher T. ; Bamman, Marcas M. ; Ferrando, Arny A. ; Young, Andrew J. ; Margolis, Lee M.
  • Note di contenuto: Intramuscular factors that modulate fat‐free mass () loss in lowlanders exposed to energy deficit during high‐altitude () sojourns remain unclear. Muscle inflammation may contribute to loss at by inducing atrophy and inhibiting myogenesis via the tumor necrosis factor ()‐like weak inducer of apoptosis () and its receptor, fibroblast growth factor‐inducible protein 14 (Fn14). To explore whether muscle inflammation modulates loss reportedly developing during sojourns, muscle inflammation, myogenesis, and proteolysis were assessed in 16 men at sea level () and following 21 days of energy deficit (−1862 ± 525 kcal/days) at high altitude (, 4300 m). Total body mass (), , and fat mass () were assessed using . Gene expression and proteolytic enzymatic activities were assessed in muscle samples collected at rest at and . Participants lost 7.2 ± 1.8 kg (<0.05); 43 ± 30% and 57 ± 30% of the lost was and , respectively. Fn14, , alpha‐receptor (‐R), ,, and paired box protein‐7 (7) were upregulated ( < 0.05) at compared to . Stepwise linear regression identified that Fn14 explained the highest percentage of variance in loss (= 0.511, <0.05). Dichotomization of volunteers into and Fn14 gene expression indicated lost less and more (28 ± 28% and 72 ± 28%, respectively) as a proportion of loss than (58 ± 26% and 42 ± 26%;  < 0.05) at . gene expression was also greater for versus ( < 0.05). These data suggest that heightened Fn14 gene expression is not catabolic and may protect during sojourns. We assessed the combined effects of high‐altitude exposure and energy deficit on muscle inflammation and examined associations between markers of inflammation and muscle mass lost. This secondary analysis from a larger study was pursued to explore potential intramuscular explanations for the interindividual variability and magnitude of muscle mass lost we observed in lowlanders exposed to 21 days of energy deficit at high altitude. We showed that 21 days of high‐altitude exposure with concomitant energy deficit, achieved with high levels of aerobic‐type activity and dietary restriction, upregulated muscle inflammation. Those with greater inflammatory responses lost less fat‐free mass and exhibited greater changes in myogenic regulatory factor gene expression. Our data suggest that heightened muscle inflammatory response to physiological and environmental stress promotes a myogenic response that may protect muscle mass by aiding in muscle regeneration.
  • Fa parte di: Physiological Reports, July 2018, Vol.6(14), pp.n/a-n/a
  • Soggetti: Hypoxia ; Interleukin‐6 ; Myogenin ; Negative Energy Balance ; Tweak
  • Tipo: Articolo
  • Identificativo: ISSN: 2051-817X ; E-ISSN: 2051-817X ; DOI: 10.14814/phy2.13801
  • Fonte: Wiley Open Access (John Wiley & Sons, Inc.)

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