Postnatal and Pubertal Skeletal Changes Contribute Predominantly to the Differences in Peak Bone Density Between C3H/HeJ and C57BL/6J Mice
作者:C. Richman、S. Kutilek、N. Miyakoshi、A. K. Srivastava、W. G. Beamer、L. R. Donahue、C. J. Rosen、J. E. Wergedal、D. J. Baylink、S. Mohan
DOI:10.1359/jbmr.2001.16.2.386
日期:——
Previous studies have shown that 60–70% of variance in peak bone density is determined genetically. The higher the peak bone density, the less likely an individual is to eventually develop osteoporosis. Therefore, the amount of bone accrued during postnatal and pubertal growth is an important determining factor in the development of osteoporosis. We evaluated the contribution of skeletal changes before, during, and after puberty to the development of peak bone density in C3H/HeJ (C3H) and C57BL/6J (B6) mice. Volumetric bone density and geometric parameters at the middiaphysis of femora were measured by peripheral quantitative computed tomography (pQCT) from days 7 to 56. Additionally, biochemical markers of bone remodeling in serum and bone extracts were quantified. Both B6 and C3H mice showed similar body and femoral weights. B6 mice had greater middiaphyseal total bone area and thinner cortices than did C3H mice. Within strains, males had thicker cortices than did females. C3H mice accumulated more minerals throughout the study, with the most rapid accumulation occurring postnatally (days 7–23) and during pubertal maturation (days 23–31). C3H mice had higher volumetric bone density as early as day 7, compared with B6 mice. Higher serum insulin‐like growth factor I (IGF‐I) was present in C3H mice postnatally at day 7 and day 14. Until day 31, B6 male and female mice had significantly higher serum osteocalcin than C3H male and female mice, respectively. Alkaline phosphatase (ALP) was found to be significantly higher in the bone extract of C3H mice compared with B6 mice at day 14. These data are consistent with and support the hypothesis that the greater amount of bone accrued during postnatal and pubertal growth in C3H mice compared with B6 mice may be caused by increased cortical thickness, increased endosteal bone formation, and decreased endosteal bone resorption.
先前的研究表明,骨密度峰值的 60-70% 差异是由遗传决定的。峰值骨密度越高,个体最终患骨质疏松症的可能性就越小。因此,出生后和青春期生长期间骨积累的量是骨质疏松症发生的重要决定因素。我们评估了青春期之前、期间和之后的骨骼变化对 C3H/HeJ (C3H) 和 C57BL/6J (B6) 小鼠骨密度峰值发展的贡献。第 7 天至第 56 天通过外周定量计算机断层扫描 (pQCT) 测量股骨中干的体积骨密度和几何参数。此外,还对血清和骨提取物中骨重塑的生化标志物进行了定量。 B6 和 C3H 小鼠均表现出相似的体重和股骨重量。 B6 小鼠比 C3H 小鼠具有更大的中干骨总面积和更薄的皮质。在品系中,雄性的皮质比雌性更厚。 C3H 小鼠在整个研究过程中积累了更多的矿物质,其中积累最快的发生在出生后(第 7-23 天)和青春期成熟期间(第 23-31 天)。与 B6 小鼠相比,C3H 小鼠早在第 7 天就具有较高的体积骨密度。 C3H 小鼠出生后第 7 天和第 14 天血清中存在较高的胰岛素样生长因子 I (IGF-I)。直到第 31 天,B6 雄性和雌性小鼠的血清骨钙素分别显着高于 C3H 雄性和雌性小鼠。第 14 天时,发现 C3H 小鼠骨提取物中的碱性磷酸酶 (ALP) 显着高于 B6 小鼠。这些数据与 C3H 小鼠出生后和青春期生长期间骨量增加的假设一致并支持这一假设与B6小鼠相比,可能是由于皮质厚度增加、骨内骨形成增加、骨内骨吸收减少所致。