Alteration of femoral bone morphology and density in COX-2-/- mice.
A role of COX-2 in pathological bone destruction and fracture repair has been established; however, few studies have been conducted to examine the involvement of COX-2 in maintaining bone mineral density and bone micro-architecture. In this study, we examined bone morphology in multiple trabecular and cortical regions within the distal and diaphyseal femur of 4-month-old wild-type and COX-2-/- mice using micro-computed tomography. Our results demonstrated that while COX-2-/- female mice had normal bone geometry and trabecular microarchitecture at 4 months of age, the male knockout mice displayed reduced bone volume fraction within the distal femoral metaphysis. Furthermore, male COX-2-/- mice had a significant reduction in cortical bone mineral density within the central cortical diaphysis and distal epiphysis and metaphysis. Consistent with the observed reduction in cortical mineral density, biomechanical testing via 4-point-bending showed that male COX-2-/- mice had a significant increase in postyield deformation, indicating a ductile bone phenotype in male COX-2-/- mice. In conclusion, our study suggests that genetic ablation of COX-2 may have a sex-related effect on cortical bone homeostasis and COX-2 plays a role in maintaining normal bone micro-architecture and density in mice.
Robertson
Galen
G
Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Xie
Chao
C
Chen
Di
D
Awad
Hani
H
Schwarz
Edward M
EM
O'Keefe
Regis J
RJ
Guldberg
Robert E
RE
Zhang
Xinping
X
D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density; D051546:Cyclooxygenase 2 / Q000235:genetics*; D005260:Female; D005269:Femur / Q000002:abnormalities* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D012737:Sex Factors; D014057:Tomography, X-Ray Computed / Q000379:methods
D051546:Cyclooxygenase 2