Sarcopenia and Muscle Aging: A Brief Overview

Abstract

The world is facing the new challenges of an aging population, and understanding the process of aging has therefore become one of the most important global concerns. Sarcopenia is a condition which is defined by the gradual loss of skeletal muscle mass and function with age. In research and clinical practice, sarcopenia is recognized as a component of geriatric disease and is a current target for drug development. In this review we define this condition and provide an overview of current therapeutic approaches. We further highlight recent findings that describe key pathophysiological phenotypes of this condition, including alterations in muscle fiber types, mitochondrial function, nicotinamide adenine dinucleotide (NAD<sup>+</sup>) metabolism, myokines, and gut microbiota, in aged muscle compared to young muscle or healthy aged muscle. The last part of this review examines new therapeutic avenues for promising treatment targets. There is still no accepted therapy for sarcopenia in humans. Here we provide a brief review of the current state of research derived from various mouse models or human samples that provide novel routes for the development of effective therapeutics to maintain muscle health during aging.

Redox Signaling and Sarcopenia: Searching for the Primary Suspect

“…With insufficient autophagy, the cell accumulates dysfunctional and malformed proteins, whereas excessive autophagy promotes muscle wasting [79]. Until the last few years, autophagy was generally thought to decrease with age [80]. This was supported by evidence that knockout of atrogenes and other autophagy proteins could induce early sarcopenia, while overexpressing atrogenes prevented losses in muscle function and extended lifespan [81].…”

Aldosterone Inhibits In Vitro Myogenesis by Increasing Intracellular Oxidative Stress via Mineralocorticoid Receptor

“…Sarcopenia is a progressive skeletal muscle disorder characterized by the accelerated loss of muscle mass and function [ 1 , 2 ]. This condition has recently drawn particular attention due to the increased likelihood of negative health outcomes, such as frailty, falls, physical weakness, poor quality of life, and mortality [ 3 , 4 ], and has been officially classified as a disease, reflecting its clinical significance [ 5 ].…”

“…This condition has recently drawn particular attention due to the increased likelihood of negative health outcomes, such as frailty, falls, physical weakness, poor quality of life, and mortality [ 3 , 4 ], and has been officially classified as a disease, reflecting its clinical significance [ 5 ]. Although the term “sarcopenia” was first used to describe age-related muscular decline [ 6 ], increasing knowledge about muscle metabolism has revealed that sarcopenia could be attributable to heterogeneous causes, including systemic inflammatory diseases, malignancy, organ failure, or medications [ 2 , 3 , 7 ]. This secondary sarcopenia involving specific causes other than aging is particularly important from a clinical perspective because of its potential reversibility.…”

Receptor-Mediated Muscle Homeostasis as a Target for Sarcopenia Therapeutics

“…Several clinical studies have shown the possibility of pharmacological interventions for sarcopenia [8,9]. For example, vitawww.e-enm.org 479 min D supplementation had the beneficial effect of increasing muscle fiber size by 10% in elderly women [10].…”