Sibonga J D, Zhang M, Evans G L, Westerlind K C, Cavolina J M, Morey-Holton E, Turner R T
Department of Orthopedics, Mayo Clinic, Rochester, MN 55905, USA.
Bone. 2000 Oct;27(4):535-40. doi: 10.1016/s8756-3282(00)00352-5.
Indirect measurements have suggested that spaceflight impairs bone elongation in rats. To test this possibility, our laboratory measured, by the fluorochrome labeling technique, bone elongation that occurred during a spaceflight experiment. The longitudinal growth rate (LGR) in the tibia of rats in spaceflight experiments (Physiological Space Experiments 1, 3, and 4 and Physiological-Anatomical Rodent Experiment 3) and in two models of skeletal unloading (hind-limb elevation and unilateral sciatic neurotomy) were calculated. The effects of an 11 day spaceflight on gene expression of cartilage matrix proteins in rat growth plates were also determined by northern analysis and are reported for the first time in this study. Measurements of longitudinal growth indicate that skeletal unloading generally did not affect LGR, regardless of age, strain, gender, duration of unloading, or method of unloading. There was, however, one exception with 34% suppression in LGR detected in slow-growing, ovariectomized rats skeletally unloaded for 8 days by hind-limb elevation. This detection of reduced LGR by hind-limb elevation is consistent with changes in steady-state mRNA levels for type II collagen (-33%) and for aggrecan (-53%) that were detected in rats unloaded by an 11 day spaceflight. The changes detected in gene expression raise concern that spaceflight may result in changes in the composition of extracellular matrix, which could have a negative impact on conversion of growth-plate cartilage into normal cancellous bone by endochondral ossification.
间接测量结果表明，太空飞行会损害大鼠的骨骼生长。为了验证这种可能性，我们实验室采用荧光染料标记技术，对太空飞行实验期间发生的骨骼生长情况进行了测量。计算了太空飞行实验（生理太空实验1、3和4以及生理 - 解剖学啮齿动物实验3）以及两种骨骼卸载模型（后肢抬高和单侧坐骨神经切断术）中大鼠胫骨的纵向生长速率（LGR）。本研究还首次通过Northern分析确定了11天太空飞行对大鼠生长板中软骨基质蛋白基因表达的影响。纵向生长测量结果表明，无论年龄、品系、性别、卸载持续时间或卸载方法如何，骨骼卸载通常不会影响LGR。然而，有一个例外情况，即通过后肢抬高对生长缓慢、卵巢切除的大鼠进行8天骨骼卸载后，检测到LGR受到34%的抑制。后肢抬高导致LGR降低这一结果，与11天太空飞行卸载的大鼠中检测到的II型胶原蛋白（-33%）和聚集蛋白聚糖（-53%）的稳态mRNA水平变化一致。基因表达的变化引发了人们的担忧，即太空飞行可能会导致细胞外基质组成发生变化，这可能会对软骨内成骨过程中生长板软骨转化为正常松质骨产生负面影响。
