title: Mechanical and material properties of cortical and trabecular bone from cannabinoid receptor-1-null (Cnr1(-/-)) mice.
abstract: The endocannabinoid system is known for its regulatory effects on bone metabolism through the cannabinoid receptors, Cnr1 and Cnr2. In this study we analysed the mechanical and material properties of long bones from Cnr1(-/-) mice on a C57BL/6 background. Tibiae and femora from 5- and 12-week-old mice were subjected to three-point bending to measure bending stiffness and yield strength. Elastic modulus, density and mineral content were measured in the diaphysis. Second moment of area (MOA2), inner and outer perimeters of the cortical shaft and trabecular fractional bone volume (BV/TV) were measured using micro-CT. In Cnr1(-/-) males and females at both ages the bending stiffness was reduced due to a smaller MOA2. Bone from Cnr1(-/-) females had a greater modulus than wild-type controls, although no differences were observed in males. BV/TV of 12-week-old Cnr1(-/-) females was greater than controls, although no difference was seen at 5-weeks. On the contrary, Cnr1(-/-) males had the same BV/TV as controls at 12-weeks while they had significantly lower values at 5-weeks. This study shows that deleting Cnr1 decreases the amount of cortical bone in both males and females at 12-weeks, but increases the amount of trabecular bone only in females.
authors.affiliation: Arthritis and Musculoskeletal Medicine, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK.
authors.forename: Aysha B
authors.initials: AB
authors.lastname: Khalid
authors.affiliation: Arthritis and Musculoskeletal Medicine, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK.
authors.forename: Simon R
authors.initials: SR
authors.lastname: Goodyear
authors.affiliation: Kosterlitz Centre for Therapeutcs, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Ross
authors.affiliation: Arthritis and Musculoskeletal Medicine, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK. Electronic address: r.aspden@abdn.ac.uk.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Aspden
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D000071556:Cancellous Bone / Q000000981:diagnostic imaging / Q000378:metabolism*; D000071538:Cortical Bone / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000378:metabolism; D055786:Gene Knockout Techniques; D008297:Male; D055595:Mechanical Phenomena; D051379:Mice; D008810:Mice, Inbred C57BL; D043884:Receptor, Cannabinoid, CB1 / Q000172:deficiency* / Q000235:genetics*; D013977:Tibia / Q000000981:diagnostic imaging / Q000378:metabolism; D055114:X-Ray Microtomography
chemical_list: C543264:Cnr1 protein, rat; D043884:Receptor, Cannabinoid, CB1
keywords: Bone; Cannabinoid receptor 1; Cortical bone; Material properties; Mechanical properties; Trabecular bone