Protective effects of chlorogenic acid on capillary regression caused by disuse muscle atrophy

High Concentrations of Nucleotides Prevent Capillary Regression during Hindlimb Unloading by Inhibiting Oxidative Stress and Enhancing Mitochondrial Metabolism of Soleus Muscles in Rats

Prolonged inactivity in skeletal muscles decreases muscle capillary development because of an imbalance between pro- and antiangiogenic signals, mitochondrial metabolism disorders, and increased oxidative stress. Nucleotides have been shown to exert a dose-dependent effect on disuse-induced muscle atrophy. However, the dose-dependent effect on capillary regression in disused muscles remains unclear. Therefore, this study investigated the dose-dependent effect of nucleotides on capillary regression due to disuse. For this purpose, Wistar rats were divided into five groups as follows: control rats fed nucleotide-free diets (CON), hindlimb-unloaded rats fed nucleotide-free diets (HU), and hindlimb-unloaded rats fed 1.0%, 2.5%, and 5.0% nucleotide diets, (HU + 1.0% NT), (HU + 2.5% NT), and (HU + 5.0% NT), respectively. Unloading increased reactive oxygen species (ROS) production and decreased mitochondrial enzyme activity, thereby decreasing the number of muscle capillaries. In contrast, 5.0% nucleotide-containing diet prevented increases in ROS production and reductions in the expression levels of NAMPT, PGC-1α, and CPT-1b proteins. Moreover, 5.0% nucleotide-containing diet prevented mitochondrial enzyme activity (such as citrate synthase and beta-hydroxy acyl-CoA dehydrogenase activity) via NAMPT or following PGC-1α upregulation, thereby preventing capillary regression. Therefore, 5.0% nucleotide-containing diet is likely to prevent capillary regression by decreasing oxidative stress and increasing mitochondrial metabolism.

Accounting Gut Microbiota as the Mediator of Beneficial Effects of Dietary (Poly)phenols on Skeletal Muscle in Aging

Sarcopenia, the age-related loss of muscle mass and function increasing the risk of disability and adverse outcomes in older people, is substantially influenced by dietary habits. Several studies from animal models of aging and muscle wasting indicate that the intake of specific polyphenol compounds can be associated with myoprotective effects, and improvements in muscle strength and performance. Such findings have also been confirmed in a smaller number of human studies. However, in the gut lumen, dietary polyphenols undergo extensive biotransformation by gut microbiota into a wide range of bioactive compounds, which substantially contribute to bioactivity on skeletal muscle. Thus, the beneficial effects of polyphenols may consistently vary across individuals, depending on the composition and metabolic functionality of gut bacterial communities. The understanding of such variability has recently been improved. For example, resveratrol and urolithin interaction with the microbiota can produce different biological effects according to the microbiota metabotype. In older individuals, the gut microbiota is frequently characterized by dysbiosis, overrepresentation of opportunistic pathogens, and increased inter-individual variability, which may contribute to increasing the variability of biological actions of phenolic compounds at the skeletal muscle level. These interactions should be taken into great consideration for designing effective nutritional strategies to counteract sarcopenia.