Mouse genetic model for bone strength and size phenotypes: NZB/B1NJ and RF/J inbred strains

• Published in: Bone (New York, N.Y.) N.Y.), 2002-12, Vol.31 (6), p.670-674
• Main Authors: Wergedal, J.E, Sheng, M.H.-C, Ackert-Bicknell, C.L, Beamer, W.G, Baylink, D.J
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biomechanical Phenomena; Bone formation; Bone size; Bone strength; Female; Femur - growth & development; Femur - physiology; Fundamental and applied biological sciences. Psychology; Genes; Mice; Mice, Inbred NZB; Mice, Inbred Strains; Models, Animal; Osteogenesis - genetics; Periosteum; Phenotype; Skeleton and joints; Species Specificity; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/S8756-3282(02)00908-0

The relationships of bone size, bone strength, and bone formation were investigated in two strains of mice, NZB/B1NJ and RF/J. Measurement of the femur midshaft size by peripheral quantitative computed tomography (pQCT) showed that the RF/J mice had a 32% greater cross-sectional area than NZB/B1NJ mice at 10 weeks of age, and a 38% greater cross-sectional area at 22 weeks of age. Body weight in the RF/J mice was 10% higher at 10 weeks but 9% lower at 22 weeks. Bone strength was determined by a three-point bending method. In agreement with the difference in bone cross-sectional area, the femurs of the RF/J mice were stronger (80% greater) and stiffer (80% greater) than the bones of the NZB/B1NJ mice. To determine whether periosteal bone formation played a role in the greater size of the RF/J mice, the mice were injected with tetracycline to label areas of new bone formation. Histomorphometrical analysis of the femur diaphysis demonstrated higher rates of periosteal bone formation (131% greater) and of periosteal forming surface (81% greater) in RF/J than in NZB/B1NJ mice. We conclude that a high rate of periosteal bone formation increases bone size and strength in RF/J mice when compared with NZB/B1NJ mice. The NZB/B1NJ and RF/J mice should be an excellent model to investigate the genes that regulate femur size and strength.