title: Skeletal muscle is an endocrine organ.
abstract: Skeletal muscle plays a key role in postural retention as well as locomotion for maintaining the physical activities of human life. Skeletal muscle has a second role as an elaborate energy production and consumption system that influences the whole body's energy metabolism. Skeletal muscle is a specific organ that engenders a physical force, and exercise training has been known to bring about multiple benefits for human health maintenance and/or improvement. The mechanisms underlying the improvement of the human physical condition have been revealed: skeletal muscle synthesizes and secretes multiple factors, and these muscle-derived factors, so-called as myokines, exert beneficial effects on peripheral and remote organs. In this short review, we focus on the third aspect of skeletal muscle function - namely, the release of multiple types of myokines, which constitute a broad network for regulating the function of remote organs as well as skeletal muscle itself. We conclusively show that skeletal muscle is one of the endocrine organs and that understanding the mechanisms of production and secretion of myokines may lead to a new pharmacological approach for treatment of clinical disorders.
authors.affiliation: Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Iizuka
authors.forename: Takuji
authors.initials: T
authors.lastname: Machida
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hirafuji
mesh_terms: D028341:Activins / Q000378:metabolism; D054392:Adipokines / Q000378:metabolism*; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology; D005353:Fibronectins / Q000378:metabolism; D038681:Follistatin / Q000378:metabolism; D006801:Humans; D007265:Inhibins / Q000378:metabolism; D007378:Interleukins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D055435:Myostatin / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D054392:Adipokines; D019485:Bone Morphogenetic Proteins; D019208:Brain-Derived Neurotrophic Factor; C487851:C1QTNF5 protein, human; C577593:FNDC5 protein, human; D005353:Fibronectins; D038681:Follistatin; D007378:Interleukins; D055435:Myostatin; D016212:Transforming Growth Factor beta; D028341:Activins; D007265:Inhibins; D003094:Collagen