Ambient hypoxia enhances the loss of muscle mass after extensive injury

T. Chaillou, N. Koulmann, A. Meunier, P. Pugnière, J. J. McCarthy, M. Beaudry, X. Bigard

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Hypoxia induces a loss of skeletal muscle mass and alters myogenesis in vitro, but whether it affects muscle regeneration in vivo following injury remains to be elucidated. We hypothesized that hypoxia would impair the recovery of muscle mass during regeneration. To test this hypothesis, the soleus muscle of female rats was injured by notexin and allowed to recover for 3, 7, 14, and 28 days under normoxia or hypobaric hypoxia (5,500 m) conditions. Hypoxia impaired the formation and growth of new myofibers and enhanced the loss of muscle mass during the first 7 days of regeneration, but did not affect the final recovery of muscle mass at 28 days. The impaired regeneration under hypoxic conditions was associated with a blunted activation of mechanical target of rapamycin (mTOR) signaling as assessed by p70S6K and 4E-BP1 phosphorylation that was independent of Akt activation. The decrease in mTOR activity with hypoxia was consistent with the increase in AMP-activated protein kinase activity, but not related to the change in regulated in development and DNA response 1 protein content. Hypoxia increased the mRNA levels of the atrogene muscle ring finger-1 after 7 days of regeneration, though muscle atrophy F box transcript levels remained unchanged. The increase in MyoD and myogenin mRNA expression with regeneration was attenuated at 7 days with hypoxia. In conclusion, our results support the notion that the enhanced loss of muscle mass observed after 1 week of regeneration under hypoxic conditions could mainly result from the impaired formation and growth of new fibers resulting from a reduction in protein synthesis and satellite cell activity.

Original languageEnglish
Pages (from-to)587-598
Number of pages12
JournalPflugers Archiv European Journal of Physiology
Volume466
Issue number3
DOIs
StatePublished - Mar 2014

Bibliographical note

Funding Information:
We thank Corinne Grégoire, Rachel Chapot, Nadine Simler, and Bernard Serrurier for helpful technical assistance and Dr Andre Peinnequin for useful discussions about RT-qPCR analysis. This work was supported by a predoctoral fellowship from the Ministère de I'Enseignement Supérieur et de la Recherche to TC and by the Association Française contre les Myopathies (grant number 13955 to MB and XB).

Keywords

  • AMPK
  • Akt/mTOR pathway
  • MRF
  • Muscle regeneration
  • Satellite cells

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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