title: Seasonal changes in bone metabolism in sheep.
abstract: There is a great need for animal models of osteoporosis and sheep are a suitable large animal that meets most requirements. Since it is known that bone mass in humans responds to seasonal changes, this study investigated natural bone metabolism in sheep in order to better define the sheep as a model for osteoporosis. Bone mineral density (BMD), trabecular structure, biochemical markers of bone formation and resorption and estrogen were analysed over a period of 18 months. The lowest BMDs, measured by peripheral quantitative computed tomography (pQCT), were observed during winter. Thereafter, a 5.1% increase in BMD was observed during spring and summer (P<0.05). Bone resorption markers showed a variable pattern, with higher values in spring compared to autumn (P<0.001). The physiological estrus phase during autumn was detected by serum estrogen levels. The findings show that it is necessary to take seasonal variations into account if sheep are used to establish an animal model for osteoporosis.
authors.affiliation: AO Research Institute, Clavadelerstrasse, CH-7270 Davos, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Arens
authors.forename: Ilonka
authors.initials: I
authors.lastname: Sigrist
authors.forename: Mauro
authors.initials: M
authors.lastname: Alini
authors.forename: Peter
authors.initials: P
authors.lastname: Schawalder
authors.forename: Erich
authors.initials: E
authors.lastname: Schneider
authors.forename: Marcus
authors.initials: M
authors.lastname: Egermann
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015519:Bone Density; D001842:Bone and Bones / Q000033:anatomy & histology / Q000378:metabolism*; D005260:Female; D012621:Seasons; D012756:Sheep / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D015415:Biomarkers; C015484:pyridinoline; C036020:deoxypyridinoline