A multimodal exercise countermeasure prevents the negative impact of head‐down tilt bed rest on muscle volume and mitochondrial health in older adults

作者：Maude Dulac, Guy Hajj‐Boutros, Vita Sonjak, Andréa Faust, Sabah N. A. Hussain, Stéphanie Chevalier, Isabelle J. Dionne, José A. Morais, Gilles Gouspillou · 发表于：The Journal of Physiology · 年份：2024 · DOI：10.1113/jp285897 · 被引用次数：17 · 研究领域：Nutrition and Health in Aging、Spaceflight effects on biology、Frailty in Older Adults

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 R...