模拟失重雌雄大鼠骨密度、骨代谢指标与骨折风险的相关性

 目的 分析模拟失重雌、雄性大鼠模型骨密度及骨代谢生化指标和生物力学之间的相关性，与骨折风险建立联系，探讨航天医疗基础工作。方法 3个月龄雌、雄性SD大鼠各20只，按照性别及是否失重分为4组。采用尾部悬吊模拟失重方法，实验4周后处死SD大鼠，双能X线吸收法(dual-energy X-ray absorption， DEXA)测定L₄椎体、股骨髁部骨密度，骨组织切片染色，ELISA法检测骨代谢生化标志物:骨碱性磷酸酶(bone alkaline phosphatase，BALP)、抗酒石酸酸性磷酸酶(tartrate-resistant acid phosphatase，TRAP)，生物力学测试骨强度。结果 悬吊组大鼠较对照组大鼠BMD均显著下降，雌性悬吊组较雄性组下降明显;组织切片悬吊组较对照组骨组织及骨细胞间隙明显增宽，细胞肿胀;BALP、TRAP雄性悬吊组分别较对照组升高3.09和1.72倍，雌性悬吊组分别较对照组升高3.43和2.14倍;悬吊组椎体的最大压缩载荷(N)、最大压缩压力(MPa)、股骨最大抗弯曲载荷(N)悬吊组较对照组显著下降。骨密度(bone mineral density，BMD)、BALP、TRAP与椎体最大力学强度Fmax相关性系数r值，雄性组分别为0.985、-0.949、-0.970，雌性组分别为0.908、-0.858、-0.921。结论 失重4周后大鼠出现明显的骨质疏松、骨小梁结构破坏、力学强度显著下降。雌性大鼠骨质疏松较雄性组明显加重。最大力学强度Fmax与骨密度成正相关，与BALP、TRAP成负相关，未来精准、便捷的骨代谢指标可能成为航天医学预测骨折风险的手段之一。

The relationship between BMD,biochemical marker parameters and fracture risk for simulated weightlessness in male and female rats

Objective To analyze the changes of BMD, biochemical marker parameters, mechanical properties in male and female rat osteoporosis models in simulated weightlessness comparatively to establish relationship and predict fracture risk.Methods 40 3-months-old SD rats were selected, 20 males and 20 females. According to the gender, they were divided into 4 groups at random: experimental group and reference group. The t Tail suspended models (TS) were measured. After 4 weeks, the rats were killed, the BMD of L₄ and femoral condyle by dual-energy X-ray absorptiometry (DEXA) were measured, the osteal tissue slices were stained by the way of poncean, the marks of bone biochemical metabolism in serum were detected by ELISA and the biomechanics was tested by biomechanical testing machine.Results The BMD of L₄ lumbar vertebrae and femoral condyle in the experimental groups are obviously lower than the reference groups. The bone metabolic biochemical markers (BLAP & TRAP) in TS groups were remarkably higher than in the reference groups. The correlation coefficient R values between Fmax and BMD, BLAP, TRAP in male groups were 0.985, －0.949, －0.970, and in female group were 0.908, －0.858, －0.921.Conclusions For 4 weeks simulated weightlessness, obvious osteoporosis, destruction of the microstructure, decrease of the mechanical strength are manifested. Fmax is positively correlated with BMD, and negative correlation for BLAP, TRAP. It is a precise and convenient bone metabolism index to predict fracture risk in space medicine and is a feasible, precise and convenient bone metabolism index to predict fracture risk in space medicine.