title: Disuse osteopenia induced by botulinum toxin is similar in skeletally mature young and aged female C57BL/6J mice.
abstract: Osteopenia and osteoporosis predominately occur in the fully grown skeleton. However, it is unknown whether disuse osteopenia in skeletally mature, but growing, mice resembles that of fully grown mice. Twenty-four 16-week-old (young) and eighteen 44-week-old (aged) female C57BL/6J mice were investigated. Twelve young and nine aged mice were injected with botulinum toxin in one hind limb; the remaining mice served as controls. The mice were euthanized after 3 weeks of disuse. The femora were scanned by micro-computed tomography (µCT) and bone strength was determined by mechanically testing the femoral mid-diaphysis and neck. At the distal femoral metaphysis, the loss of trabecular bone volume fraction (BV/TV) differed between the young and aged mice. However, at the distal femoral epiphysis, no age-dependent differences were observed. Thinning of the trabeculae was not affected by the age of the mice at either the distal femoral metaphysis or the epiphysis. Furthermore, the aged mice lost more bone strength at the femoral mid-diaphysis, but not at the femoral neck, compared to the young mice. In general, the bone loss induced by botulinum toxin did not differ substantially between young and aged mice. Therefore, the loss of bone in young mice resembles that of aged mice, even though they are not fully grown.
authors.affiliation: Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, 8000, Aarhus C, Denmark. jbve@biomed.au.dk.
authors.forename: Jens Bay
authors.identifier: http://orcid.org/0000-0003-1973-3127
authors.initials: JB
authors.lastname: Vegger
authors.affiliation: Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, 8000, Aarhus C, Denmark.
authors.forename: Annemarie
authors.initials: A
authors.lastname: Brüel
authors.affiliation: Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, 8000, Aarhus C, Denmark.
authors.forename: Mikkel Bo
authors.initials: MB
authors.lastname: Brent
authors.affiliation: Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, 8000, Aarhus C, Denmark.
authors.forename: Jesper Skovhus
authors.initials: JS
authors.lastname: Thomsen
mesh_terms: D015502:Absorptiometry, Photon; D000375:Aging / Q000473:pathology*; D000818:Animals; D001696:Biomechanical Phenomena; D001835:Body Weight; D001846:Bone Development; D001851:Bone Diseases, Metabolic / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D001905:Botulinum Toxins; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D021621:Imaging, Three-Dimensional; D008810:Mice, Inbred C57BL; D009929:Organ Size; D055114:X-Ray Microtomography
chemical_list: D001905:Botulinum Toxins
keywords: Aging; Immobilization; Mechanical testing; Mice; Micro-CT