Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, Ohio 43210.
Endocr Rev. 2014 Aug;35(4):648-70. doi: 10.1210/er.2013-1051. Epub 2014 Mar 27.
Most organisms display endogenously produced ∼ 24-hour fluctuations in physiology and behavior, termed circadian rhythms. Circadian rhythms are driven by a transcriptional-translational feedback loop that is hierarchically expressed throughout the brain and body, with the suprachiasmatic nucleus of the hypothalamus serving as the master circadian oscillator at the top of the hierarchy. Appropriate circadian regulation is important for many homeostatic functions including energy regulation. Multiple genes involved in nutrient metabolism display rhythmic oscillations, and metabolically related hormones such as glucagon, insulin, ghrelin, leptin, and corticosterone are released in a circadian fashion. Mice harboring mutations in circadian clock genes alter feeding behavior, endocrine signaling, and dietary fat absorption. Moreover, misalignment between behavioral and molecular circadian clocks can result in obesity in both rodents and humans. Importantly, circadian rhythms are most potently synchronized to the external environment by light information and exposure to light at night potentially disrupts circadian system function. Since the advent of electric lights around the turn of the 20th century, exposure to artificial and irregular light schedules has become commonplace. The increase in exposure to light at night parallels the global increase in the prevalence of obesity and metabolic disorders. In this review, we propose that exposure to light at night alters metabolic function through disruption of the circadian system. We first provide an introduction to the circadian system, with a specific emphasis on the effects of light on circadian rhythms. Next we address interactions between the circadian system and metabolism. Finally, we review current experimental and epidemiological work directly associating exposure to light at night and metabolism.
大多数生物体表现出内源性的生理和行为约 24 小时波动，称为昼夜节律。昼夜节律是由一个转录 - 翻译反馈环驱动的，该反馈环在大脑和身体中呈层次表达，下丘脑视交叉上核作为层次结构的主生物钟振荡器。适当的昼夜节律调节对于许多稳态功能很重要，包括能量调节。参与营养代谢的多个基因显示出节律性振荡，代谢相关的激素如胰高血糖素、胰岛素、胃饥饿素、瘦素和皮质酮以昼夜节律的方式释放。时钟基因发生突变的小鼠改变摄食行为、内分泌信号和膳食脂肪吸收。此外，行为和分子生物钟之间的失同步可能导致啮齿动物和人类肥胖。重要的是，昼夜节律通过光信息与外部环境最有效地同步，夜间暴露于光下可能会破坏昼夜节律系统功能。自 20 世纪之交电灯问世以来，人工和不规则光照时间表的暴露已变得司空见惯。夜间暴露于光的增加与肥胖和代谢紊乱的全球发病率增加平行。在这篇综述中，我们提出夜间暴露于光会通过破坏昼夜节律系统来改变代谢功能。我们首先介绍昼夜节律系统，特别强调光对昼夜节律的影响。接下来我们讨论昼夜节律系统与代谢之间的相互作用。最后，我们回顾了直接将夜间暴露于光与代谢相关联的当前实验和流行病学工作。
