Microgravity is well-known to induce Osteopenia. However, the combined effects of microgravity and radiation that commonly exist in space have not been broadly elucidated. This research investigates the combined effects on MC3T3-E1 cells and rat femurs. In MC3T3-E1 cells, simulated microgravity and X-ray radiation, alone or combination, show decreased cell activity, increased apoptosis rates by flow cytometric analysis, and decreased Runx2 and increased Caspase-3 mRNA and protein expressions. In rat femurs, simulated microgravity and X-ray radiation, alone or combination, show increased bone loss by micro-CT test and Masson staining, decreased serum BALP levels and Runx2 mRNA expressions, and increased serum CTX-1 levels and Caspase-3 mRNA expressions. The strongest effect is observed in the combined group in MC3T3-E1 cells and rat femurs. These findings suggest that the combination of microgravity and radiation exacerbates the effects of either treatment alone on MC3T3-E1 cells and rat femurs.

众所周知，微重力会引起骨减少症。然而，尚未广泛阐明空间中普遍存在的微重力和辐射的综合影响。这项研究调查了对MC3T3-E1细胞和大鼠股骨的联合作用。在MC3T3-E1细胞中，单独或组合的模拟微重力和X射线辐射显示细胞活性降低，流式细胞仪分析显示凋亡率增加，Runx2和Caspase-3 mRNA和蛋白质表达降低。在大鼠股骨中，单独或联合进行的微重力和X射线模拟显示，通过micro-CT测试和Masson染色显示骨丢失增加，血清BALP水平和Runx2 mRNA表达降低，血清CTX-1水平和Caspase-3 mRNA增加表达式。在MC3T3-E1细胞和大鼠股骨的联合组中观察到最强的作用。