Characterising Bone Material Composition and Structure in the Ovariectomized (OVX) Rat Model of Osteoporosis
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The ovariectomized (OVX) rat model is well established in investigations of osteoporosis and osteoporotic therapies. Advent of techniques such as Fourier-transform infrared (FTIR) spectroscopy and small angle X-ray scattering (SAXS) facilitate characterization of bone composition and mineral structure, respectively, which are key determinants of bone strength. Limited publications exist on the implementation of these techniques in the OVX rat model. At 12 weeks of age, female Sprague–Dawley rats were either sham-operated (n = 6) or ovariectomized (n = 6) and sacrificed 18 weeks later. L2 lumbar vertebrae and proximal tibiae were assessed by µCT, FTIR and SAXS. Presence of extensive trabecular deterioration in the µCT data confirmed the onset of osteoporosis. FTIR compositional parameters were determined including measures of degree of mineralization, crystallinity, collagen maturity and acid phosphate content. Mineral crystal thickness was determined from the SAXS data using two approaches available in literature. Compositionally, a decline in the heterogeneity of acid phosphate content was observed while measures of crystallinity and collagen maturity remained unaltered. Using an iterative curve fitting method, OVX-induced increases in the mineral crystal thickness of 3.8 and 7.8 % (p < 0.05) were noted in the trabecular of the vertebra and tibia, respectively. In conclusion, implementation of FTIR and SAXS techniques in the OVX rat model, identified no significant compositional changes while substantiating thickening of the mineral crystals as a general structural feature of OVX-induced osteoporosis in rats.
KeywordsOsteoporosis Bone composition Bone structure Fourier-transform infrared spectroscopy FTIR Small angle X-ray scattering SAXS
Funding for this study from the European Commission (FRACQUAL-293434) and the Swedish Governmental Agency for Innovation Systems (VINNOVA) is acknowledged. Beamtime was generously granted at the I911-SAXS beamline and the D7 beamline at MAX IV Laboratory, Lund, Sweden. The authors would also like to gratefully acknowledge the technical assistance of Mea Pelkonen, Ana Labrador (I911-SAXS beamline) and Anders Engdahl (D7 beamline).
Conflict of interest
Authors Neashan Mathavan, Mikael J. Turunen, Magnus Tägil and Hanna Isaksson declare that they have no conflict of interest.
Statement of animal rights and informed consent
All procedures performed in this study were in accordance with the ethical standards of Lund University, Sweden, where the study was conducted. All institutional and national guidelines for the care and use of laboratory animals were followed.
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