Banu J, Wang L, Kalu D N
Department of Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, USA.
Calcif Tissue Int. 2003 Aug;73(2):196-201. doi: 10.1007/s00223-002-1072-z.
It has been hypothesized that increase in muscle mass increases the strain on bone resulting in increase in bone mass. The aim of the present study was to determine the effects of increased muscle mass on bone. A colony of transgenic mice that overexpress hIGF-I in muscle, resulting in larger muscles, was established. Six-month-old heterozygous and wild type males were used in this study. The tibial diaphysis, femoral diaphysis and distal femoral metaphysis were analyzed using pQCT densitometry. Heterozygous animals had significantly higher body weight, muscle weight and muscle area when compared with wild type animals. Tibia and femur of the heterozygous mice had significantly higher weights and lengths. The tibial and femoral diaphyses of heterozygous animals had significantly higher cortical bone area, cortical bone mineral content, cortical bone mineral density, cortical thickness and periosteal perimeter when compared with wild type animals. In the distal femoral metaphysis, the total bone area and the cancellous bone area of heterozygous mice were significantly higher than those of wild type animals. In conclusion, increased muscle mass was associated with bigger bones in animals overexpressing IGF-I. Only pure cortical bone increased in both area and mineral content in these animals; cancellous bone, however, increased only in area and not in mineral content and density.
据推测，肌肉量增加会增加骨骼所承受的应变，从而导致骨量增加。本研究的目的是确定肌肉量增加对骨骼的影响。建立了一个在肌肉中过度表达hIGF-I从而导致肌肉更大的转基因小鼠群体。本研究使用了6个月大的杂合子和野生型雄性小鼠。使用外周定量计算机断层扫描（pQCT）骨密度测定法分析胫骨骨干、股骨骨干和股骨远端干骺端。与野生型动物相比，杂合子动物的体重、肌肉重量和肌肉面积显著更高。杂合子小鼠的胫骨和股骨重量及长度显著更高。与野生型动物相比，杂合子动物的胫骨和股骨骨干的皮质骨面积、皮质骨矿物质含量、皮质骨矿物质密度、皮质厚度和骨膜周长显著更高。在股骨远端干骺端，杂合子小鼠的总骨面积和松质骨面积显著高于野生型动物。总之，在过度表达IGF-I的动物中，肌肉量增加与骨骼更大有关。在这些动物中，只有纯皮质骨的面积和矿物质含量增加；然而，松质骨仅面积增加，矿物质含量和密度并未增加。
