title: Alteration of femoral bone morphology and density in COX-2-/- mice.
abstract: 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.
authors.affiliation: Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Galen
authors.initials: G
authors.lastname: Robertson
authors.forename: Chao
authors.initials: C
authors.lastname: Xie
authors.forename: Di
authors.initials: D
authors.lastname: Chen
authors.forename: Hani
authors.initials: H
authors.lastname: Awad
authors.forename: Edward M
authors.initials: EM
authors.lastname: Schwarz
authors.forename: Regis J
authors.initials: RJ
authors.lastname: O'Keefe
authors.forename: Robert E
authors.initials: RE
authors.lastname: Guldberg
authors.forename: Xinping
authors.initials: X
authors.lastname: Zhang
mesh_terms: 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
chemical_list: D051546:Cyclooxygenase 2