模拟失重与骨组织的细胞凋亡★

背景：空间骨丢失主要表现为成骨细胞、骨细胞活性减弱，而包括Fas蛋白在内的诸多因素可调节成骨细胞、骨细胞的增殖和分化并最终调控骨形成。 目的：观察失重对骨组织中细胞凋亡的影响。 方法：5周龄SPF级雄性SD大鼠36只，随机分为尾吊模拟失重组及对照组。建立大鼠尾吊模拟失重模型，建模后7，14，21 d，使用自动生化仪检测大鼠血清中钙、磷、碱性磷酸酶含量，放射免疫分析法测定骨钙素含量，原位细胞凋亡检测技术检测骨组织中细胞凋亡，免疫组化方法检测骨组织中Fas蛋白含量。 结果与结论：尾吊模拟失重组大鼠血清中碱性磷酸酶、骨钙素含量均显著低于对照组(P < 0.05)，但血钙、磷浓度均较相应对照组升高，骨组织中成骨细胞、骨细胞及骨髓间充质细胞凋亡指数、骨组织中Fas抗原含量均高于相应对照组(P < 0.01)。说明尾部悬吊模拟失重增加骨组织中Fas蛋白表达，从而增加大鼠骨组织中成骨细胞、骨细胞及骨髓间充质细胞凋亡。 关键词：尾吊；模拟失重；生化；骨钙素；细胞凋亡；Fas蛋白

Simulated weightlessness and apoptosis in bone tissue

BACKGROUND: Bone loss in space presents with weakened activity of osteoblasts and osteocytes. Many factors, including Fas protein, can regulate the proliferation and differentiation of osteoblasts and osteocytes, ultimately, regulate bone formation. OBJECTIVE: To observe the effects of weightlessness on apoptosis of bone tissues. METHODS: Thirty-six male Sprague Dawley rats were randomly assigned to simulated weightlessness and control groups. The rats were suspended by the tail for simulating weightlessness. At 7, 14 and 21 days after simulated weightlessness, contents of serum calcium, phosphorus, and alkaline phosphatase were observed by an automated analyzer. The level of bone gla protein was measured by radio immunoassay. Condition of cell apoptosis in bone tissues was detected by in situ death detection. The expressions of Fas protein were detected with SP immunohistochemical method. RESULTS AND CONCLUSION: The contents of serum bone gla protein and alkaline phosphatase were significantly lower in the simulated weightlessness group than those in corresponding control group (P < 0.05), whereas serum calcium, phosphorus concentration were increased, and the apoptotic index of osteoblasts, osteocytes and bone marrow stromal cells were higher than that in corresponding control group (P < 0.01). Skeletal unloading in rats induces an increase in Fas protein expression, thus, increase the apoptosis of osteoblasts, osteocytes and bone marrow cells.