title: Degenerative and regenerative features of myofibers differ among skeletal muscles in a murine model of muscular dystrophy.
abstract: Skeletal muscle myofibers constantly undergo degeneration and regeneration. Histopathological features of 6 skeletal muscles (cranial tibial [CT], gastrocnemius, quadriceps femoris, triceps brachii [TB], lumbar longissimus muscles, and costal part of the diaphragm [CPD]) were compared using C57BL/10ScSn-Dmdmdx(mdx) mice, a model for muscular dystrophy versus control, C57BL/10 mice. Body weight and skeletal muscle mass were lower in mdx mice than the control at 4 weeks of age; these results were similar at 6-30 weeks. Additionally, muscular lesions were observed in all examined skeletal muscles in mdx mice after 4 weeks, but none were noted in the controls. Immunohistochemical staining revealed numerous paired box 7-positive satellite cells surrounding the embryonic myosin heavy chain-positive regenerating myofibers, while the number of the former and staining intensity of the latter decreased as myofiber regeneration progressed. Persistent muscular lesions were observed in skeletal muscles of mdx mice between 4 and 14 weeks of age, and normal myofibers decreased with age. Number of muscular lesions was lowest in CPD at all ages examined, while the ratio of normal myofibers was lowest in TB at 6 weeks. In CT, TB, and CPD, Iba1-positive macrophages, the main inflammatory cells in skeletal muscle lesions, showed a significant positive correlation with the appearance of regenerating myofibers. Additionally, B220-positive B-cells showed positive and negative correlation with regenerating and regenerated myofibers, respectively. Our data suggest that degenerative and regenerative features of myofibers differ among skeletal muscles and that inflammatory cells are strongly associated with regenerative features of myofibers in mdx mice.
authors.affiliation: Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo, 060-0818, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Ikeda
authors.affiliation: Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo, 060-0818, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ichii
authors.affiliation: Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo, 060-0818, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Otsuka-Kanazawa
authors.affiliation: Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo, 060-0818, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo, 060-0818, Japan.
authors.forename: Yaser Hosny Ali
authors.initials: YH
authors.lastname: Elewa
authors.affiliation: Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo, 060-0818, Japan. y-kon@vetmed.hokudai.ac.jp.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kon
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D051379:Mice; D018101:Mice, Inbred mdx / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009137:Muscular Dystrophy, Animal / Q000503:physiopathology*
keywords: Costal part of the diaphragm; Inflammation; Muscular dystrophy; Skeletal muscle remodeling; Triceps brachii; mdx mouse