title: Low-level laser irradiation promotes the recovery of atrophied gastrocnemius skeletal muscle in rats.
abstract: Low-level laser (LLL) irradiation promotes proliferation of muscle satellite cells, angiogenesis and expression of growth factors. Satellite cells, angiogenesis and growth factors play important roles in the regeneration of muscle. The objective of this study was to examine the effect of LLL irradiation on rat gastrocnemius muscle recovering from disuse muscle atrophy. Eight-week-old rats were subjected to hindlimb suspension for 2 weeks, after which they were released and recovered. During the recovery period, rats underwent daily LLL irradiation (Ga-Al-As laser; 830 nm; 60 mW; total, 180 s) to the right gastrocnemius muscle through the skin. The untreated left gastrocnemius muscle served as the control. In conjunction with LLL irradiation, 5-bromo-2-deoxyuridine (BrdU) was injected subcutaneously to label the nuclei of proliferating cells. After 2 weeks, myofibre diameters of irradiated muscle increased in comparison with those of untreated muscle, but did not recover back to normal levels. Additionally, in the superficial region of the irradiated muscle, the number of capillaries and fibroblast growth factor levels exhibited significant elevation relative to those of untreated muscle. In the deep region of irradiated muscle, BrdU-positive nuclei of satellite cells and/or myofibres increased significantly relative to those of the untreated muscle. The results of this study suggest that LLL irradiation can promote recovery from disuse muscle atrophy in association with proliferation of satellite cells and angiogenesis.
authors.affiliation: Unit of Physical Therapy and Occupational Therapy Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8052, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Nakano
authors.forename: Hideki
authors.initials: H
authors.lastname: Kataoka
authors.forename: Jyunya
authors.initials: J
authors.lastname: Sakamoto
authors.forename: Tomoki
authors.initials: T
authors.lastname: Origuchi
authors.forename: Minoru
authors.initials: M
authors.lastname: Okita
authors.forename: Toshiro
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D002196:Capillaries / Q000473:pathology / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D019417:Hindlimb Suspension; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D028022:Low-Level Light Therapy; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects*; D009133:Muscular Atrophy / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D032448:Myoblasts, Skeletal / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D009210:Myofibrils / Q000473:pathology; D018919:Neovascularization, Physiologic / Q000528:radiation effects; D051381:Rats; D017208:Rats, Wistar; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects
chemical_list: D016222:Fibroblast Growth Factor 2; D007334:Insulin-Like Growth Factor I; D001973:Bromodeoxyuridine