Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang, Hunan, China; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA.
Department of Medical Education, WWAMI Medical Education Program, University of Wyoming, Laramie, WY, USA.
Life Sci Space Res (Amst). 2017 Nov;15:62-68. doi: 10.1016/j.lssr.2017.08.004. Epub 2017 Aug 12.
During spaceflight, crewmembers are subjected to biomechanical and biological challenges including microgravity and radiation. In the skeleton, spaceflight leads to bone loss, increasing the risk of fracture. Studies utilizing hindlimb suspension (HLS) as a ground-based model of spaceflight often neglect the concomitant effects of radiation exposure, and even when radiation is accounted for, it is often delivered at a high-dose rate over a very short period of time, which does not faithfully mimic spaceflight conditions. This study was designed to investigate the skeletal effects of low-dose rate gamma irradiation (8.5 cGy gamma radiation per day for 20 days, amounting to a total dose of 1.7 Gy) when administered simultaneously to disuse from HLS. The goal was to determine whether continuous, low-dose rate radiation administered during disuse would exacerbate bone loss in a murine HLS model. Four groups of 16 week old female C57BL/6 mice were studied: weight bearing + no radiation (WB+NR), HLS + NR, WB + radiation exposure (WB+RAD), and HLS+RAD. Surprisingly, although HLS led to cortical and trabecular bone loss, concurrent radiation exposure did not exacerbate these effects. Our results raise the possibility that mechanical unloading has larger effects on the bone loss that occurs during spaceflight than low-dose rate radiation.
在航天飞行中，航天员会受到生物力学和生物学方面的挑战，包括微重力和辐射。在骨骼中，航天飞行会导致骨质流失，增加骨折的风险。利用后肢悬吊（HLS）作为基于地面的航天飞行模型的研究通常忽略了辐射暴露的伴随影响，即使考虑到辐射，辐射通常也是在很短的时间内以高剂量率进行的，这并不能真实模拟航天飞行条件。本研究旨在研究低剂量率伽马辐射（每天 8.5cGy 伽马辐射，共 20 天，总剂量为 1.7Gy）与 HLS 导致的失用同时存在时对骨骼的影响。目的是确定在失用期间连续给予低剂量率辐射是否会加剧小鼠 HLS 模型中的骨质流失。研究了四组 16 周龄雌性 C57BL/6 小鼠：负重+无辐射（WB+NR）、HLS+NR、WB+辐射暴露（WB+RAD）和 HLS+RAD。令人惊讶的是，尽管 HLS 导致皮质骨和小梁骨丢失，但同时进行的辐射暴露并没有加剧这些影响。我们的结果提出了这样一种可能性，即在航天飞行中发生的骨质流失中，机械卸载的影响比低剂量率辐射更大。
