ABSTRACT

The aim of this study was to demonstrate for the first time in Tarabul’s gerbils (Gerbillus tarabuli), 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 Gerbilus tarabuli, 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.

摘要

这项研究的目的是第一次证明塔拉布尔的沙鼠（tarberuli），同时暴露于两种主要环境压力（光和噪声污染）对体温节律和焦虑行为的影响。七个组（每个组由6个成年雄性沙鼠组成）接受标准的LD周期（12 L：12D），并在恒定条件下（总黑暗，DD）在08:00 h亮起并在20:00 h灭灯夜间暴露于光（PEL：18 L：6D），且在08:00 h开灯，在02:00 h关灯，模仿了城市周边地区长时间暴露在光污染下，听觉应力（TNS）暴露在80 dB ，以及结合了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。结果揭示了该物种的首次存在体温的内生昼夜节律，周期为23.8±0.04 h。晚上长时间暴露在光线下（PEL）会导致明显的相位延迟（02 h 09 min±0.16 h），顶峰期（峰值时间）发生在04:42±0.13 h而不是02:33±0.21 h 。每晚暴露于TNS 4小时会导致节律幅度显着增加和节律规律性降低（TNS的稳健性为73.26％，而对照组为82.32）。虽然将TNS和PEL结合使用可显着延迟Tb节律的相位3小时10分钟（顶峰期从06:39±0.37 h代替02:33±0.21 h），但振幅增加，并显着降低了节奏的稳定性（在PEL＆TNS中的耐用性为67.25％，而在对照条件下为82.32）。PEL＆TNS和TNS环境在沙鼠中引起了重要的压力，突出表现为线穿越次数的减少和在露天测试中心区域花费的时间显着减少。此外，高架迷宫测试显示PEL＆TNS和TNS条件的沙鼠显着走访了最少的张开双臂，并在其中花费了较短的时间。此外，与对照和PEL条件相比，这些条件导致更少的活动（武器中条目的总数）。这些结果清楚地表明，在沙漠地区，城市周围的光和噪声污染扰乱了昼夜节律成分，并改变了塔拉布尔沙鼠的焦虑状态。高架迷宫测试显示，PEL＆TNS和TNS条件的沙鼠显着拜访了最少的张开双臂，并在其中花费了较短的时间。此外，与对照和PEL条件相比，这些条件导致更少的活动（武器中条目的总数）。这些结果清楚地表明，在沙漠地区，城市周围的光和噪声污染扰乱了昼夜节律成分，并改变了塔拉布尔沙鼠的焦虑状态。高架迷宫测试显示，PEL＆TNS和TNS条件的沙鼠显着拜访了最少的张开双臂，并在其中花费了较短的时间。此外，与对照和PEL条件相比，这些条件导致更少的活动（武器中条目的总数）。这些结果清楚地表明，在沙漠地区，城市周围的光和噪声污染扰乱了昼夜节律成分，并改变了塔拉布尔沙鼠的焦虑状态。