title: Strontium and bone nanostructure in normal and ovariectomized rats investigated by scanning small-angle X-ray scattering.
abstract: The effect of SrCl(2) treatment on bone nanostructure in a rat ovariectomy model was studied using scanning small-angle X-ray scattering (sSAXS). Twelve 6-month-old female Wistar rats were used. Six animals were ovariectomized (+ovx) and six were left intact after sham surgery (-ovx). Six animals, three +ovx and three -ovx, were treated with 4 mmol SrCl(2) (aq)/kg/day (+Sr), whereas the remaining six received placebo (-Sr) for 140 days. Rats were labeled with flourochromes at days 7, 126, and 136. Femoral cross sections were studied using fluorescence microscopy, scanning electron microscopy including energy-dispersive X-ray analysis, and sSAXS. The SAXS data comprised about 5,500 measurements and provided information about mineral crystal thickness and orientation in new and old bone. The newly formed bone contained higher levels of Sr(2+) in +Sr than in -Sr animals, indicating that the Sr(2+) was incorporated into the new bone. Mineral plates were significantly thicker in old bone, 2.62 nm (95% CI 2.58-2.66), than in new bone, 2.41 nm (95% CI 2.36-2.46). Surprisingly, mineral plates in new bone were significantly thicker (2.52 [95% CI 2.47-2.57] nm vs. 2.41 [95% CI 2.36-2.46] nm, P = 0.017) in +ovx rats than in -ovx rats. However, no significant effect of SrCl(2) on mineral plate thicknesses in new bone was observed. The statistical model yielded estimates of the difference in bone mineral plate thickness induced by Sr. The estimated effect of Sr was -0.09 (95% CI -0.21 to 0.03) and 0.02 (95% CI -0.10 to 0.14) nm for new bone in -ovx and +ovx rats, respectively.
authors.affiliation: Department of Endocrinology and Metabolism C, Aarhus University Hospital, Arhus, Denmark. mbunger@inano.dk
authors.forename: Mathias H
authors.initials: MH
authors.lastname: Bünger
authors.forename: Hans
authors.initials: H
authors.lastname: Oxlund
authors.forename: Toke K
authors.initials: TK
authors.lastname: Hansen
authors.forename: Søren
authors.initials: S
authors.lastname: Sørensen
authors.forename: Bo M
authors.initials: BM
authors.lastname: Bibby
authors.forename: Jesper S
authors.initials: JS
authors.lastname: Thomsen
authors.forename: Bente L
authors.initials: BL
authors.lastname: Langdahl
authors.forename: Flemming
authors.initials: F
authors.lastname: Besenbacher
authors.forename: Jan S
authors.initials: JS
authors.lastname: Pedersen
authors.forename: Henrik
authors.initials: H
authors.lastname: Birkedal
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D001842:Bone and Bones / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure*; D002113:Calcification, Physiologic / Q000187:drug effects; D005260:Female; D005269:Femur / Q000187:drug effects; D008856:Microscopy, Fluorescence; D049329:Nanostructures / Q000737:chemistry; D010052:Ovariectomy; D010919:Placebos; D051381:Rats; D017208:Rats, Wistar; D053838:Scattering, Small Angle; D013324:Strontium / Q000494:pharmacology*; D014961:X-Ray Diffraction / Q000662:veterinary
chemical_list: D050071:Bone Density Conservation Agents; D010919:Placebos; C025700:strontium chloride; D013324:Strontium