UCLA Institute of the Environment and Sustainability, 619 Charles E. Young Drive East, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095-1496, USA.
UCLA Department of Integrative Biology and Physiology, 612 Charles E. Young Drive East, Box 957246, Los Angeles, CA 90095-7246, USA.
J Exp Biol. 2024 Jul 15;227(14). doi: 10.1242/jeb.247235.
The influence of light spectral properties on circadian rhythms is of substantial interest to laboratory-based investigation of the circadian system and to field-based understanding of the effects of artificial light at night. The trade-offs between intensity and spectrum regarding masking behaviors are largely unknown, even for well-studied organisms. We used a custom LED illumination system to document the response of wild-type house mice (Mus musculus) to 1-h nocturnal exposure of all combinations of four intensity levels (0.01, 0.5, 5 and 50 lx) and three correlated color temperatures (CCT; 1750, 1950 and 3000 K). Higher intensities of light (50 lx) suppressed cage activity substantially, and consistently more for the higher CCT light (91% for 3000 K, 53% for 1750 K). At the lowest intensity (0.01 lx), mean activity was increased, with the greatest increases for the lowest CCT (12.3% increase at 1750 K, 3% increase at 3000 K). Multiple linear regression confirmed the influence of both CCT and intensity on changes in activity, with the scaled effect size of intensity 3.6 times greater than that of CCT. Activity suppression was significantly lower for male than for female mice. Assessment of light-evoked cFos expression in the suprachiasmatic nucleus at 50 lx showed no significant difference between high and low CCT exposure. The significant differences by spectral composition illustrate a need to account for light spectrum in circadian studies of behavior, and confirm that spectral controls can mitigate some, but certainly not all, of the effects of light pollution on species in the wild.
光的光谱性质对昼夜节律的影响是实验室研究昼夜节律系统和野外理解人工夜间光照效应的重要课题。即使对于研究充分的生物，关于强度和光谱在掩蔽行为方面的权衡关系也知之甚少。我们使用定制的 LED 照明系统记录了野生型小家鼠（Mus musculus）对 1 小时夜间暴露于四种强度水平（0.01、0.5、5 和 50 lx）和三种相关色温（CCT；1750、1950 和 3000 K）的所有组合的反应。更高强度的光（50 lx）显著抑制了笼内活动，且对更高 CCT 的光抑制作用更明显（3000 K 时为 91%，1750 K 时为 53%）。在最低强度（0.01 lx）下，平均活动增加，最低 CCT 时增加幅度最大（1750 K 时增加 12.3%，3000 K 时增加 3%）。多元线性回归证实了 CCT 和强度对活动变化的影响，强度的影响规模大小是 CCT 的 3.6 倍。雄性小鼠的活动抑制作用显著低于雌性小鼠。在 50 lx 时，评估光诱发的视交叉上核中的 cFos 表达，在高和低 CCT 暴露之间没有显著差异。光谱组成的显著差异表明，在行为的昼夜节律研究中需要考虑光的光谱，并且证实光谱控制可以减轻一些但肯定不是所有的对野生动物的光污染影响。
