模拟失重状态下成骨细胞胰岛素样生长因子1基因表达与降钙素的干预

背景：航天飞行、长期卧床等低重力负荷状态会引起骨吸收和骨形成的代谢紊乱，导致骨质疏松。有研究显示降钙素有直接促进成骨细胞增殖的作用，并可增加成骨细胞胰岛素样生长因子1 mRNA的表达。目的：观察降钙素和体外模拟失重状态对成骨细胞功能及胰岛素样生长因子1基因表达的影响。方法：采用二次酶消化法提取新生SD大鼠颅骨的成骨细胞，凝胶化形成成骨细胞海藻酸钠微包囊后进行实验。实验分为正常重力组、模拟失重组、模拟失重+降钙素(10，40，80 IU/L)组。将细胞置于模拟失重三维回转培养器中培养72 h后，检测成骨细胞的增殖、凋亡及碱性磷酸酶活性；采用RT-PCR 方法检测胰岛素样生长因子1、碱性磷酸酶、骨钙素mRNA的表达。结果与结论：与正常重力组比较，模拟失重组细胞增殖率及培养基中碱性磷酸酶活性均明显降低(P < 0.01)，胰岛素样生长因子1、骨钙素、碱性磷酸酶mRNA表达减少，凋亡增多；与模拟失重组比较，模拟失重+降钙素组细胞增殖率，胰岛素样生长因子1、骨钙素、碱性磷酸酶mRNA表达均有所增加，但无剂量依赖关系。说明降钙素可通过上调胰岛素样生长因子1 mRNA表达改善模拟失重条件下成骨细胞的增殖与分泌功能。

Interventional effect of calcitonin on insulin like growth factor 1 gene expression in osteoblasts under simulated microgravity

BACKGROUND: Space flight, bed-ridden state of low-gravity load will cause bone metabolic disorder which includes bone absorption and bone formation abnormal, leading to bone loss, decreased bone mineral density. Researches have showed that calcitonin can promote osteoblastic activity and mRNA expression of insulin like growth factor 1 (IGF-1).OBJECTIVE: To observe the effects of calcitonin on osteoblastic activity and mRNA expression of IGF-1 in vitro under simulated microgravity.METHODS: Osteoblasts were collected from newborn SD mouse by means of double enzyme digestion. The osteoblasts were polymerized and encapsulated the cells inside alginate carriers in Cacl2 solution. All cells were assigned into normal gravity, simulated microgravity and simulated microgravity + calcitonin (10, 40 and 80 IU/L) groups. Osteoblasts were cultured for 72 hours in simulated microgravity and normal gravity in the three-dimensional rotating vessel. The proliferation and apoptosis of the osteoblasts and alkaline phosphatase (ALP) activity were detected, in addition, the expression of IGF-1, ALP and osteocalcin were measured by RT-PCR. RESULTS AND CONCLUSION: Compared with the normal gravity group, the osteoblasts proliferation rate and secretion of ALP were decreased, and the expression of IGF-1, ALP, osteocalcin mRNA were reduced in the simulated microgravity group (P < 0.01). Compared with the simulated microgravity group, osteoblasts proliferation rate, IGF-1, ALP, osteocalcin mRNA were increased in the simulated microgravity + calcitonin group, but no dose-dependent manner could be found. The findings demonstrated that calcitonin can improve osteoblast proliferation and secretion functions via up-regulating IGF-1 mRNA expression in simulated microgravity.