title: Total water, phosphorus relaxation and inter-atomic organic to inorganic interface are new determinants of trabecular bone integrity.
abstract: Bone is the living composite biomaterial having unique structural property. Presently, there is a considerable gap in our understanding of bone structure and composition in the native state, particularly with respect to the trabecular bone, which is metabolically more active than cortical bones, and is readily lost in post-menopausal osteoporosis. We used solid-state nuclear magnetic resonance (NMR) to compare trabecular bone structure and composition in the native state between normal, bone loss and bone restoration conditions in rat. Trabecular osteopenia was induced by lactation as well as prolonged estrogen deficiency (bilateral ovariectomy, Ovx). Ovx rats with established osteopenia were administered with PTH (parathyroid hormone, trabecular restoration group), and restoration was allowed to become comparable to sham Ovx (control) group using bone mineral density (BMD) and µCT determinants. We used a technique combining (1)H NMR spectroscopy with (31)P and (13)C to measure various NMR parameters described below. Our results revealed that trabecular bones had diminished total water content, inorganic phosphorus NMR relaxation time (T1) and space between the collagen and inorganic phosphorus in the osteopenic groups compared to control, and these changes were significantly reversed in the bone restoration group. Remarkably, bound water was decreased in both osteopenic and bone restoration groups compared to control. Total water and T1 correlated strongly with trabecular bone density, volume, thickness, connectivity, spacing and resistance to compression. Bound water did not correlate with any of the microarchitectural and compression parameters. We conclude that total water, T1 and atomic space between the crystal and organic surface are altered in the trabecular bones of osteopenic rats, and PTH reverses these parameters. Furthermore, from these data, it appears that total water and T1 could serve as trabecular surrogates of micro-architecture and compression strength.
authors.affiliation: Centre of Biomedical Research, SGPGIMS Campus, Lucknow, India.
authors.forename: Ratan Kumar
authors.initials: RK
authors.lastname: Rai
authors.affiliation: Division of Endocrinology and Center for Research on Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow, India.
authors.forename: Tarun
authors.initials: T
authors.lastname: Barbhuyan
authors.affiliation: Centre of Biomedical Research, SGPGIMS Campus, Lucknow, India.
authors.forename: Chandan
authors.initials: C
authors.lastname: Singh
authors.affiliation: Division of Endocrinology and Center for Research on Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow, India.
authors.forename: Monika
authors.initials: M
authors.lastname: Mittal
authors.affiliation: Division of Endocrinology and Center for Research on Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow, India.
authors.forename: Mohd Parvez
authors.initials: MP
authors.lastname: Khan
authors.affiliation: Centre of Biomedical Research, SGPGIMS Campus, Lucknow, India.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Sinha
authors.affiliation: Division of Endocrinology and Center for Research on Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow, India.
authors.forename: Naibedya
authors.initials: N
authors.lastname: Chattopadhyay
mesh_terms: D000818:Animals; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000378:metabolism* / Q000473:pathology; D001842:Bone and Bones / Q000737:chemistry* / Q000378:metabolism* / Q000473:pathology; D004838:Epiphyses / Q000737:chemistry / Q000473:pathology; D005260:Female; D009682:Magnetic Resonance Spectroscopy; D019906:Nuclear Magnetic Resonance, Biomolecular; D010052:Ovariectomy; D010758:Phosphorus / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D014867:Water / Q000737:chemistry / Q000378:metabolism
chemical_list: D014867:Water; D010758:Phosphorus