The Center for Peace, Hiroshima University, Hiroshima 730-0053, Japan.
Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan.
Int J Environ Res Public Health. 2020 Aug 5;17(16):5638. doi: 10.3390/ijerph17165638.
Investigating initial behavioral changes caused by irradiation of animals might provide important information to aid understanding of early health effects of radiation exposure and clinical features of radiation injury. Although previous studies in rodents suggested that radiation exposure leads to reduced activity, detailed properties of the effects were unrevealed due to a lack of proper statistical analysis, which is needed to better elucidate details of changes in locomotor activity. Ten-week-old male Wistar rats were subjected to single point external whole-body irradiation with Co gamma rays at 0, 2.0, 3.5, and 5.0 Gy (four rats per group). Infrared sensors were used to continuously record the locomotor activity of each rat. The cumulative number of movements during the night was defined as "activity" for each day. A non-linear mixed effects model accounting for individual differences and daily fluctuation of activity was applied to analyze the rats' longitudinal locomotor data. Our statistical method revealed characteristics of the changes in locomotor activity after radiation exposure, showing that (1) reduction in activity occurred immediately-and in a dose-dependent manner-after irradiation and (2) recovery to pre-irradiation levels required almost one week, with the same recovery rate in each dose group.
研究动物照射后引起的初始行为变化可能为了解辐射暴露的早期健康影响和辐射损伤的临床特征提供重要信息。尽管啮齿动物的先前研究表明辐射暴露会导致活动减少，但由于缺乏适当的统计分析，这些影响的详细特征尚未揭示，而统计分析对于更好地阐明运动活动变化的细节是必需的。将 10 周龄雄性 Wistar 大鼠用 Co 伽马射线进行单次点全身照射，剂量分别为 0、2.0、3.5 和 5.0 Gy（每组 4 只大鼠）。使用红外传感器连续记录每只大鼠的运动活动。将夜间的运动总次数定义为每天的“活动量”。应用一种考虑个体差异和活动日内波动的非线性混合效应模型分析大鼠的纵向运动数据。我们的统计方法揭示了辐射暴露后运动活动变化的特征，表明（1）照射后活动立即减少，且呈剂量依赖性；（2）恢复到照射前水平需要近一周时间，每个剂量组的恢复速度相同。
