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 ⁶⁰Co 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.

中文翻译：

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定量分析单个60Coγ射线照射对大鼠自发活动的时间依赖性变化的影响。

调查动物辐照引起的初始行为变化可能会提供重要信息，以帮助了解辐射暴露对健康的早期影响以及辐射损伤的临床特征。尽管先前在啮齿类动物中的研究表明，辐射暴露会导致活动减少，但由于缺乏适当的统计分析，因此尚未揭示该作用的详细特性，而这需要更好地阐明运动活动变化的细节。对十周大的雄性Wistar大鼠进行⁶⁰点单点体外全身照射γ射线分别为0、2.0、3.5和5.0 Gy（每组四只大鼠）。使用红外传感器连续记录每只大鼠的运动能力。夜间的累计移动次数定义为每天的“活动”。应用非线性混合效应模型解决个体的纵向运动数据，该模型考虑了个体差异和活动的日常波动。我们的统计方法揭示了放射线照射后运动能力变化的特征，表明（1）放射线照射后活性立即降低并且以剂量依赖的方式发生，并且（2）放射线恢复到需要近一周的水平，每个剂量组的回收率相同。