INTRODUCTION: Hindlimb unloading-induced muscle atrophy is often assessed after a homeostatic state is established, thus overlooking the early adaptations that are critical to developing this pattern of atrophy. METHODS: Muscle function and physiology were characterized at 0, 1, 3, 7, and 14 days of hindlimb suspension (HS). RESULTS: Reductions in muscle mass were maximal by Day 14 of HS. Functional strength and isolated muscle strength were reduced. MyHC-I and -IIa expressing fibers were reduced in size by Day 7 in the soleus and by Day 14 in the gastrocnemius (MyHC-I fibers only). Atrogin-1 and MuRF1 expression was increased by Day 1 in both the calf and tibialis anterior while IGF-1 expression was significantly reduced on Day 3. Phosphorylation of Akt was reduced on Day 14. CONCLUSIONS: Insight into these early changes in response to HS improves understanding of the molecular and functional changes that lead to muscle atrophy.
INTRODUCTION: Hindlimb unloading-induced muscle atrophy is often assessed after a homeostatic state is established, thus overlooking the early adaptations that are critical to developing this pattern of atrophy. METHODS: Muscle function and physiology were characterized at 0, 1, 3, 7, and 14 days of hindlimb suspension (HS). RESULTS: Reductions in muscle mass were maximal by Day 14 of HS. Functional strength and isolated muscle strength were reduced. MyHC-I and -IIa expressing fibers were reduced in size by Day 7 in the soleus and by Day 14 in the gastrocnemius (MyHC-I fibers only). Atrogin-1 and MuRF1 expression was increased by Day 1 in both the calf and tibialis anterior while IGF-1 expression was significantly reduced on Day 3. Phosphorylation of Akt was reduced on Day 14. CONCLUSIONS: Insight into these early changes in response to HS improves understanding of the molecular and functional changes that lead to muscle atrophy.
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Authors: Allan F Pagano; Rémi Demangel; Thomas Brioche; Elodie Jublanc; Christelle Bertrand-Gaday; Robin Candau; Claude A Dechesne; Christian Dani; Anne Bonnieu; Guillaume Py; Angèle Chopard Journal: PLoS One Date: 2015-12-02 Impact factor: 3.240