Department of Zoology, Mizoram University, Aizawl, Mizoram 796004, India.
Department of Zoology, Mizoram University, Aizawl, Mizoram 796004, India.
J Photochem Photobiol B. 2024 Apr;253:112885. doi: 10.1016/j.jphotobiol.2024.112885. Epub 2024 Mar 6.
The daily light/dark cycle affects animals' learning, memory, and cognition. Exposure to insufficient daylight illumination negatively impacts emotion and cognition, leading to seasonal affective disorder characterized by depression, anxiety, low motivation, and cognitive impairment in diurnal animals. However, how this affects memory, learning, and cognition in nocturnal rodents is largely unknown. Here, we studied the effect of daytime light illuminance on memory, learning, cognition, and expression of mRNA levels in the hippocampus, thalamus, and cortex, the higher-order learning centers. Two experiments were performed. In experiment one, rats were exposed to 12 L:12D (12 h light and 12 h dark) with a 10, 100, or 1000 lx daytime light illuminance. After 30 days, various behavioral tests (novel object recognition test, hole board test, elevated plus maze test, radial arm maze, and passive avoidance test) were performed. In experiment 2, rats since birth were raised either under constant bright light (250 lx; LL) or a daily light-dark cycle (12 L:12D). After four months, behavioral tests (novel object recognition test, hole board test, elevated plus maze test, radial arm maze, passive avoidance test, Morris water maze, and Y-maze tests) were performed. At the end of experiments, rats were sampled, and mRNA expression of Brain-Derived Neurotrophic Factor (Bdnf), Tyrosine kinase (Trk), microRNA132 (miR132), Neurogranin (Ng), Growth Associated Protein 43 (Gap-43), cAMP Response Element-Binding Protein (Crebp), Glycogen synthase kinase-3β (Gsk3β), and Tumour necrosis factor-α (Tnf-α) were measured in the hippocampus, cortex, and thalamus of individual rats. Our results show that exposure to bright daylight (100 and 1000 lx; experiment 1) or constant light (experiment 2) compromises memory, learning, and cognition. Suppressed expression levels of these mRNA were also observed in the hypothalamus, cortex, and thalamus. These results suggest that light affects differently to different groups of animals.
日常的明暗周期会影响动物的学习、记忆和认知。暴露在光照不足的环境中会对情绪和认知产生负面影响，导致季节性情感障碍，其特征是昼行性动物出现抑郁、焦虑、低动力和认知障碍。然而，这种情况如何影响夜间活动的啮齿动物的记忆、学习和认知，在很大程度上尚不清楚。在这里，我们研究了白天光照照度对记忆、学习、认知以及海马体、丘脑和大脑皮层等高级学习中心的 mRNA 水平表达的影响。进行了两项实验。在实验一中，大鼠暴露于 12L:12D（12 小时光照和 12 小时黑暗），光照照度分别为 10、100 或 1000lx。30 天后，进行了各种行为测试（新物体识别测试、洞板测试、高架十字迷宫测试、放射臂迷宫测试和被动回避测试）。在实验二中，大鼠从出生起就被饲养在持续明亮的光照（250lx；LL）或每日明暗循环（12L:12D）中。四个月后，进行了行为测试（新物体识别测试、洞板测试、高架十字迷宫测试、放射臂迷宫测试、被动回避测试、Morris 水迷宫测试和 Y 迷宫测试）。在实验结束时，对大鼠进行采样，并测量个体大鼠海马体、大脑皮层和丘脑中的脑源性神经营养因子（Bdnf）、酪氨酸激酶（Trk）、微 RNA132（miR132）、神经颗粒蛋白（Ng）、生长相关蛋白 43（Gap-43）、cAMP 反应元件结合蛋白（Crebp）、糖原合成酶激酶-3β（Gsk3β）和肿瘤坏死因子-α（Tnf-α）的 mRNA 表达。我们的结果表明，暴露于明亮的日光（100 和 1000lx；实验 1）或持续光照（实验 2）会损害记忆、学习和认知。这些 mRNA 的表达水平也在下丘脑、大脑皮层和丘脑观察到下降。这些结果表明光照对不同的动物群体有不同的影响。
