Evaluation of an Antioxidant and Anti-inflammatory Cocktail Against Human Hypoactivity-Induced Skeletal Muscle Deconditioning

Abstract

Understanding the molecular pathways involved in the loss of skeletal muscle mass and function induced by muscle disuse is a crucial issue in the context of spaceflight as well as in the clinical field, and development of efficient countermeasures is needed. Recent studies have reported the importance of redox balance dysregulation as a major mechanism leading to muscle wasting. Our study aimed to evaluate the effects of an antioxidant/anti-inflammatory cocktail (741 mg of polyphenols, 138 mg of vitamin E, 80 μg of selenium, and 2.1 g of omega-3) in the prevention of muscle deconditioning induced by long-term inactivity. The study consisted of 60 days of hypoactivity using the head-down bed rest (HDBR) model. Twenty healthy men were recruited; half of them received a daily antioxidant/anti-inflammatory supplementation, whereas the other half received a placebo. Muscle biopsies were collected from the vastus lateralis muscles before and after bedrest and 10 days after remobilization. After 2 months of HDBR, all subjects presented muscle deconditioning characterized by a loss of muscle strength and an atrophy of muscle fibers, which was not prevented by cocktail supplementation. Our results regarding muscle oxidative damage, mitochondrial content, and protein balance actors refuted the potential protection of the cocktail during long-term inactivity and showed a disturbance of essential signaling pathways (protein balance and mitochondriogenesis) during the remobilization period. This study demonstrated the ineffectiveness of our cocktail supplementation and underlines the complexity of redox balance mechanisms. It raises interrogations regarding the appropriate nutritional intervention to fight against muscle deconditioning.

Keywords: antioxidants; cell signaling; inactivity; muscle wasting; oxidative stress.

Figure 1

Representative time axis of the experiment.

Figure 2

Isometric maximal voluntary contraction (MVC) torques before and after the HDBR experiment: torques (N.m) generated during isometric MVC in (A) knee and (B) ankle extension and flexion positions. Data bars represent means ± SEM. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001: difference between time condition (pre vs. post). ^$p < 0.05: difference between groups (cocktail vs. placebo).

Figure 3

Cross-sectional areas (CSAs) of muscle fibers from vastus lateralis biopsies: (A) global CSA of muscle fibers (μm²) before (pre), after (post), and 10 days after the end (recovery) of 2-months HDBR; (B) variation of CSA of Type I, Type II, and Type IIa muscle fibers, between different time conditions. Data bars represent means ± SEM. ^*p < 0.05, ^**p < 0.01: difference between time condition. ^$difference between group treatment (cocktail vs. placebo).

Figure 4

Distribution (%) of muscle fibers in vastus lateralis samples, in the different time-points and conditions of the HDBR experiment: proportion of (A) Type I, (B) Type IIa and (C) Type IIx muscle fibers before (pre), after (post), and 10 days after the end (recovery) of 2-months HDBR. Data bars represent means ± SEM. ^*p < 0.05, ^**p < 0.01: difference between time condition. ^$p < 0.05, ^$$p < 0.01: difference between group treatment (cocktail vs. placebo).

Figure 5

Oxidative stress parameters in the different time-points and conditions of the HDBR experiment: (A) determination of oxidative damage to lipids using 4-hydroxynonenal and (B) carbonylated protein levels. Protein content of antioxidant enzymes, (C) glutathione peroxidase, and (D) catalase. Data bars represent means ± SEM. ^*p < 0.05, ^**p < 0.01: difference between time condition.

Figure 6

Oxidative metabolism parameters in the different time-points and conditions of the HDBR experiment: determination of (A) citrate synthase; (B) COX IV; (C) cytochrome c, and (D) PGC1-α protein levels. Data bars represent means ± SEM. ^*p < 0.05, ^**p < 0.01: difference between time condition.

Figure 7

Protein balance parameters in the different time-points and conditions of the HDBR experiment: determination of synthesis pathway markers, (A) Pras40; (B) 4E-BP1; (C) eIF2α and degradation pathway markers (D) ULK1; (E) ATG7; and (F) LC3 protein levels. Data bars represent means ± SEM. ^*p < 0.05, ^**p < 0.01: difference between time condition. ^$p < 0.05: difference between groups (cocktail vs. placebo) for the same time condition.