Neurobiology Laboratory, Laboratory of Organism's Biology and Physiology, USTHB, Algiers, Algeria.
Comparative Anatomy Unit, Veterinary Medicine School, Hassan II Institute of Agronomy and Veterinary Medicine, Rabat, Morocco.
Chronobiol Int. 2021 Mar;38(3):415-425. doi: 10.1080/07420528.2020.1862858. Epub 2021 Jan 12.
The aim of this study was to demonstrate for the first time in Tarabul's gerbils , the effects of simultaneous exposure to two major environmental stressors - light and noise pollutions - on the body temperature rhythm and anxious behavior. Seven groups, each consisting of 6 adult male gerbils, were subjected to a standard LD cycle (12 L:12D) with lights on at 08:00 h and off at 20:00 h, constant conditions (total darkness, DD), prolonged nighttime exposure to light (PEL: 18 L:6D) with lights on at 08:00 h and off at 02:00 h, mimicking prolonged exposure to light pollution in peri-urban areas, exposure to auditory stress (TNS) of 80 dB, and conditions combining PEL&TNS. The body temperature circadian rhythm was recorded, and behavioral tests were performed at the end of experimental phases. The results revealed the existence, for the first time in , of an endogenous circadian rhythm of body temperature with a period of 23.8 ± 0.04 h. Prolonged exposure to light at night (PEL) induced a significant phase delay (02 h 09 min ± 0.16 h) of the rhythm, with an acrophase (peak time) occurring at 04:42 ± 0.13 h instead of 02:33 ± 0.21 h. Exposure to TNS for 4 hours per night induced a significant increase of the amplitude of the rhythm and a decrease of the rhythm regularity (robustness of 73.26% in TNS vs. 82.32 in control condition). While combining TNS and PEL significantly delayed the phase of the Tb rhythm by 3 h 10 min (acrophase at 06:39 ± 0.37 h instead of 02:33 ± 0.21 h), increased the amplitude, and significantly reduced the stability of the rhythm (robustness of 67.25% in PEL&TNS vs. 82.32 in control condition). PEL&TNS and TNS environments induce an important stress in gerbils highlighted by a significant decrease of the number of line crossings and time spent in the center area of the open field test. Furthermore, elevated plus maze test revealed gerbils of the PEL&TNS and TNS conditions significantly visited the lowest number of open arms and spent a shorter amount of time in it. In addition, these conditions were responsible for less activity (total number of entries in arms) than in the control and PEL conditions. These results indicate clearly that in the desert area, peri-urban light and noise pollutions disturb the circadian rhythm components and alter the behavior of Tarabul's gerbils inducing an anxious state.
这项研究的目的是首次在 Tarabul 沙鼠中证明，同时暴露于两种主要环境压力源——光和噪声污染——对体温节律和焦虑行为的影响。七个实验组，每组由 6 只成年雄性沙鼠组成，经历了标准的 LD 周期（12L:12D），光照时间为 08:00，关闭时间为 20:00，持续光照条件（全暗，DD），长时间夜间暴露于光（PEL：18L:6D），光照时间为 08:00，关闭时间为 02:00，模拟城市周边地区长时间暴露于光污染，听觉应激（TNS）为 80dB，以及结合 PEL&TNS 的条件。记录体温昼夜节律，并在实验阶段结束时进行行为测试。结果显示，首次在 Tarabul 沙鼠中存在内源性体温昼夜节律，其周期为 23.8±0.04h。夜间长时间暴露于光（PEL）导致节律显著延迟（02 小时 09 分钟±0.16 小时），峰时出现在 04:42±0.13 小时，而不是 02:33±0.21 小时。每晚暴露于 TNS 4 小时会导致节律幅度显著增加，并降低节律规律性（TNS 时的稳健性为 73.26%，对照条件为 82.32%）。而将 TNS 和 PEL 结合使用时，会导致 Tb 节律的相位延迟 3 小时 10 分钟（峰时在 06:39±0.37 小时，而不是 02:33±0.21 小时），同时增加节律幅度，并显著降低节律稳定性（PEL&TNS 时的稳健性为 67.25%，对照条件为 82.32%）。PEL&TNS 和 TNS 环境会导致沙鼠产生显著的应激，表现在旷场试验中穿越线的数量和在中央区域停留的时间明显减少。此外，高架十字迷宫试验显示，PEL&TNS 和 TNS 条件下的沙鼠明显访问了较少的开放臂，并在其中停留的时间较短。此外，这些条件下的活动量（进入臂的总次数）比对照和 PEL 条件下要少。这些结果清楚地表明，在沙漠地区，城市周边的光和噪声污染干扰了 Tarabul 沙鼠的昼夜节律成分，并改变了它们的行为，导致其处于焦虑状态。
