Westerlind K C, Turner R T
Department of Orthopedics and Biochemistry and Molecular Biology, Mayo Graduate School of Medicine, Rochester, Minnesota, USA.
J Bone Miner Res. 1995 Jun;10(6):843-8. doi: 10.1002/jbmr.5650100603.
Dynamic weight bearing is important for normal growth and maintenance of the skeleton in humans and laboratory animals. Transforming growth factor-beta (TGF-beta) has been implicated as having autocrine and paracrine actions in bone. The purpose of this study was to examine mRNA levels of TGF-beta in skeletal tissues of growing male rats following skeletal unweighting during an 11-day spaceflight. Animals were sacrificed 5-8 h after the skeleton was reloaded. Spaceflight resulted in decreases in cortical bone area and periosteal bone formation, but no change in medullary area and endocortical bone formation. In addition, spaceflight had no effect on longitudinal bone growth. TGF-beta was reduced relative to the ground controls in the hindlimb periosteum, but was not significantly altered in the growth zone of the tibial metaphysis. Similarly, mRNA levels for type I collagen were reduced in the periosteum, but not in the metaphysis of flight animals. The results suggest a potential role of TGF-beta as an intermediate in the signal transduction pathway for mechanical loading. Further, they indicate skeletal tissue compartment-dependent changes in mRNA levels for TGF-beta following weightlessness.
动态负重对于人类和实验动物骨骼的正常生长及维持至关重要。转化生长因子-β（TGF-β）被认为在骨骼中具有自分泌和旁分泌作用。本研究的目的是检测11天太空飞行期间骨骼失重后生长中的雄性大鼠骨骼组织中TGF-β的mRNA水平。在骨骼重新负重5 - 8小时后处死动物。太空飞行导致皮质骨面积和骨膜骨形成减少，但骨髓面积和内皮质骨形成无变化。此外，太空飞行对纵向骨生长无影响。与地面对照组相比，后肢骨膜中的TGF-β减少，但胫骨近端生长区未发生显著改变。同样，飞行动物骨膜中I型胶原蛋白的mRNA水平降低，但干骺端未降低。结果表明TGF-β在机械负荷信号转导途径中可能作为一种中间体发挥作用。此外，它们表明失重后TGF-β的mRNA水平存在骨骼组织区室依赖性变化。
