Age-Related Changes in Trabecular Architecture Differ in Female and Male C57BL/6J Mice

Abstract

We used µCT and histomorphometry to assess age-related changes in bone architecture in male and female C57BL/6J mice. Deterioration in vertebral and femoral trabecular microarchitecture begins early, continues throughout life, is more pronounced at the femoral metaphysis than in the vertebrae, and is greater in females than males.Introduction: Despite widespread use of mice in the study of musculoskeletal disease, the age-related changes in murine bone structure and the relationship to whole body BMD changes are not well characterized. Thus, we assessed age-related changes in body composition, whole body BMD, and trabecular and cortical microarchitecture at axial and appendicular sites in mice. Materials and Methods: Peripheral DXA was used to assess body composition and whole body BMD in vivo, and CT and histomorphometry were used to measure trabecular and cortical architecture in excised femora, tibia, and vertebrae in male and female C57BL/6J mice at eight time-points between 1 and 20 mo of age (n ‫ס‬ 6-9/group). Results: Body weight and total body BMD increased with age in male and female, with a marked increase in body fat between 6 and 12 mo of age. In contrast, trabecular bone volume (BV/TV) was greatest at 6-8 wk of age and declined steadily thereafter, particularly in the metaphyseal region of long bones. Age-related declines in BV/TV were greater in female than male. Trabecular bone loss was characterized by a rapid decrease in trabecular number between 2 and 6 mo of age, and a more gradual decline thereafter, whereas trabecular thickness increased slowly over life. Cortical thickness increased markedly from 1 to 3 mo of age and was maintained or slightly decreased thereafter. Conclusions: In C57BL/6J mice, despite increasing body weight and total body BMD, age-related declines in vertebral and distal femoral trabecular bone volume occur early and continue throughout life and are more pronounced in females than males. Awareness of these age-related changed in bone morphology are critical for interpreting the skeletal response to pharmacologic interventions or genetic manipulation in mice.

Inhibiting activin-A signaling stimulates bone formation and prevents cancer-induced bone destruction in vivo

“…Trabecular volume (BV/TV, %) and number (Tb.N, /mm) were determined using Scanco software in a region 360 mm proximal to the growth plate extending 1.8 mm proximally. (36) In the preliminary longitudinal study of 5T2MM-bearing mice, tibas were radiographed using a Faxitron (Hewlett-Packard, Lincolnshire, IL, USA), and osteolytic lesion number was counted. For interventional 5T2MM studies, in which mice were treated with ActRIIA.muFc from week 1 after tumor cell inoculation, long bones were scanned on a Skyscan mCT 1172 (Skyscan, Kontich, Belgium) at 50 kV and 200 mA using a 0.5-mm aluminium filter and a detection pixel size of 4.3 mm 2 .…”

Global genome splicing analysis reveals an increased number of alternatively spliced genes with aging

“…Femur measurements showed age‐related growth that was consistent with that of previous reports (Fig. 1H) (Glatt et al ., 2007; Sohal et al ., 2009). Femur mid‐diaphysis thickness was consistent with increased periosteal perimeter (Fig.…”

Autophagy controls mesenchymal stem cell properties and senescence during bone aging

“…In C57BL/6J mice, patterns of age‐related changes in trabecular bone are quite similar to humans. Mice older than twelve months showed dramatic bone decrease especially (Glatt, Canalis, Stadmeyer, & Bouxsein, 2007). Moreover, bone loss in females is more associated with oestrogen.…”