Dulac 2024 J Physiol

From Bioblast
Publications in the MiPMap
Dulac M, Hajj-Boutros G, Sonjak V, Faust A, Hussain SNA, Chevalier S, Dionne IJ, Morais JA, Gouspillou G (2024) A multimodal exercise countermeasure prevents the negative impact of head-down tilt bed rest on muscle volume and mitochondrial health in older adults. J Physiol [Epub ahead of print]. https://doi.org/10.1113/jp285897

Β» PMID: 38878232 Open Access

Dulac Maude, Hajj-Boutros Guy, Sonjak Vita, Faust Andrea, Hussain Sabah NA, Chevalier Stephanie, Dionne Isabelle J, Morais Jose A, Gouspillou Gilles (2024) J Physiol

Abstract: Mitochondrial dysfunctions are thought to contribute to muscle atrophy and weakness that develop during ageing and mechanical unloading caused by immobilization, bed rest and microgravity. Older adults are at greater risk of developing muscle and mitochondrial dysfunctions in response to unloading. Although exercise is well known to promote muscle and mitochondrial health, its protective effect during mechanical unloading in older adults remains largely unexplored. Here, we investigated the impact of 14 days of head-down tilt bed rest (HDBR) with and without a multimodal exercise countermeasure in older men and women (55-65 years). Leg muscle volume was assessed using magnetic resonance imaging. Biopsies of the vastus lateralis were performed to assess markers of mitochondrial content, respiration, reactive oxygen species (ROS) production and calcium retention capacity (mCRC). Indices of mitochondrial quality control (MQC), including markers of fusion (MFN1 and 2), fission (Drp1), mitophagy (Parkin) and autophagy (p62 and LC3I and II) were measured using immunoblots. Muscle cross-sections were stained for neural cell adhesion molecule (NCAM, a marker of denervation). HDBR triggered muscle atrophy, decreased mitochondrial content and respiration and increased mitochondrial ROS production. HDBR had no impact on mCRC or MQC markers but increased markers of autophagy and denervation. Exercise prevented the deleterious effects of HDBR on leg muscle volume, mitochondrial ROS production and markers of autophagy and denervation. Exercise also increased mitochondrial content and respiration without altering mCRC and MQC markers. Collectively, our results indicate that an exercise countermeasure that can be performed in bed is effective in protecting muscle and mitochondrial health during HDBR in older adults.

Conditions associated with muscle unloading, such as immobilization, bed rest or microgravity, result in muscle atrophy and weakness, particularly in older adults. Mitochondrial dysfunctions are thought to contribute to muscle atrophy caused by unloading and ageing. However, whether exercise can counteract the deleterious effects of unloading in older adults remains largely unexplored. Here, we report that older adults exposed to 14 days of head-down tilt bed rest (HDBR) displayed upper leg muscle atrophy, a decrease in mitochondrial content and respiration, an increase in H2O2 emission, and an increase in autophagy and denervation markers. No impact of HDBR on mitochondrial quality control was observed. A multimodal exercise countermeasure prevented the deleterious effects of HDBR on upper leg muscle volume, mitochondrial reactive oxygen species emission, and markers of autophagy and denervation and increased mitochondrial content and respiration. These findings highlight the effectiveness of exercise in promoting muscle and mitochondrial health in older adults undergoing bed rest. β€’ Keywords: Ageing, Atrophy, Autophagy, Disuse, Inactivity, Mitochondria, Mitochondrial dynamics, Neuromuscular junction, Skeletal muscle, Space flight, Weakness β€’ Bioblast editor: Plangger M β€’ O2k-Network Lab: CA Montreal Gouspillou G


Labels: MiParea: Respiration, Exercise physiology;nutrition;life style  Pathology: Aging;senescence 

Organism: Human  Tissue;cell: Skeletal muscle  Preparation: Permeabilized tissue 


Coupling state: LEAK, OXPHOS  Pathway: F, N, NS, ROX  HRR: Oxygraph-2k, O2k-Fluorometer 

2024-06, AmR 

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