title: Spontaneous myopathy in the SJL/J mouse: pathology and strength loss.
abstract: Myopathy has been found to develop spontaneously in 100% of SJL/J mice between 6 and 8 months of age. Extent of muscular involvement and mouse strength were quantified in SJL/J mice and Balb/c control mice 2-16 months old. Muscle from young SJL/J mice exhibited histopathological abnormalities and occasional inflammatory infiltrate. By 6 months, 78% of SJL/J mice had developed active myopathy. By 8 months, all SJL/J mice examined had active disease with a mean of 12.9% of muscle fibers affected. Replacement of muscle fibers by fat and/or collagen began at 10 months and was pronounced by 14 months. Significant decreases in strength scores (total body pulling force) at 6 months and 10 months of age reflected the onset of active myopathy and the onset of muscle degeneration, respectively. The spontaneous onset and 100% incidence of myopathy in the SJL/J mouse line should provide a useful model for idiopathic myopathy.
authors.affiliation: Department of Neuroimmunology, Colorado Neurological Institute, Englewood, USA.
authors.forename: A H
authors.initials: AH
authors.lastname: Weller
authors.forename: S A
authors.initials: SA
authors.lastname: Magliato
authors.forename: K P
authors.initials: KP
authors.lastname: Bell
authors.forename: N L
authors.initials: NL
authors.lastname: Rosenberg
mesh_terms: D000367:Age Factors; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D018485:Muscle Fibers, Skeletal / Q000648:ultrastructure*; D009220:Myositis / Q000473:pathology*