David Valentin, Lafage-Proust Marie-Hélène, Laroche Norbert, Christian Alexandre, Ruegsegger Peter, Vico Laurence
Institut National de la Santé et de la Recherche Médicale, Laboratoire de Biologie du Tissu Osseux, University of Saint- Etienne, Saint-Etienne, France.
Am J Physiol Endocrinol Metab. 2006 Mar;290(3):E440-7. doi: 10.1152/ajpendo.00293.2004.
The goal of this study was to determine, through a longitudinal follow-up, whether sex influences bone adaptation during simulated weightlessness. Twelve-week-old male and female Wistar rats were hindlimb unweighted for 2 wk, and the time course of bone alteration was monitored in vivo by means of densitometry and unbiased three-dimensional quantitative microcomputed tomography at 7 and 14 days. Compared with male rats, female rats had twice more cancellous bone volume at the proximal tibia at baseline, and this bone volume continued to increase, whereas in males it stabilized. Conversely, cortical area was greater in males than in females, and in both sexes cortical bone was still expanding. Hindlimb unloading resulted in larger reductions in males than in females in both cortical and cancellous compartments. In females, trabecular thickness and number decreased mildly, whereas in males trabecular number was dramatically reduced. In both sexes, the trabecular network became less connected and more rod-like shaped. Bone cellular activities evaluated by histomorphometry showed decreased bone formation rate in both sexes and increased resorption activity only in males. In conclusion, in female rats unloaded-related cancellous alterations reversed the growing process, whereas in males, which show lower growth process, it induced an accentuation of age-related cancellous bone changes for most of the parameters.
本研究的目的是通过纵向随访，确定性别是否会影响模拟失重期间的骨骼适应性。12周龄的雄性和雌性Wistar大鼠后肢去负荷2周，在第7天和第14天通过骨密度测定和无偏三维定量显微计算机断层扫描在体内监测骨骼改变的时间进程。与雄性大鼠相比，雌性大鼠在基线时胫骨近端的松质骨体积是雄性的两倍，并且该骨体积持续增加，而雄性大鼠的骨体积则稳定下来。相反，雄性大鼠的皮质面积大于雌性大鼠，并且在两性中皮质骨仍在扩展。后肢卸载导致雄性大鼠皮质和松质骨部分的减少幅度大于雌性大鼠。在雌性大鼠中，小梁厚度和数量轻度下降，而在雄性大鼠中，小梁数量显著减少。在两性中，小梁网络的连接性降低，且更呈杆状。通过组织形态计量学评估的骨细胞活性显示，两性的骨形成率均降低，仅雄性大鼠的骨吸收活性增加。总之，在雌性大鼠中，与卸载相关的松质骨改变逆转了生长过程，而在生长过程较低的雄性大鼠中，对于大多数参数，它加剧了与年龄相关的松质骨变化。
