Age-related changes in bone mineral density and cross-sectional area in mice

Objective Age-relatde changes in bone mineral density(BMD),cross-sectional area of the tibia in vivo were measured by peripheral quantitative computed tomography(pQCT),and the correlation was analyzed,providing the reference for the resarch on bone metabolism in mice. Methods Thirty female mice were divided into age groups of 4,6,8,10 and 12 weeks, 6 each. The mice were fixed with holder under anesthesia.BMD and cross-sectional area were measured by pQCT(Stratec,XCT,Research SA)at 1.4 and 4.0 mm from the proximal epiphysis of tibia. Results The body weight of female mice increased quickly during 4-12 weeks of age,and showed age dependemcy with significant correlation (r=0.963,P0.001);the total and cortical BMD have increased at 4-12 weeks as well as corss-sectional area,and they were correlated significantly.But trabecular BMD increased slowly without correlation during the period,and the maximal trabecular area appeared at 8 weeks of age. Conclusion The pQCT precisely defermines various regions of mouse tibia in vivo. Therefore, measurement in vivo is useful for the monitoring of skeletal changes in mice.Mice at the ages of 8-10 weeks are suitable for development of osteoporosis models.