Department of Neuroscience, Ohio State University, Columbus, OH 43210, USA.
Proc Natl Acad Sci U S A. 2010 Oct 26;107(43):18664-9. doi: 10.1073/pnas.1008734107. Epub 2010 Oct 11.
The global increase in the prevalence of obesity and metabolic disorders coincides with the increase of exposure to light at night (LAN) and shift work. Circadian regulation of energy homeostasis is controlled by an endogenous biological clock that is synchronized by light information. To promote optimal adaptive functioning, the circadian clock prepares individuals for predictable events such as food availability and sleep, and disruption of clock function causes circadian and metabolic disturbances. To determine whether a causal relationship exists between nighttime light exposure and obesity, we examined the effects of LAN on body mass in male mice. Mice housed in either bright (LL) or dim (DM) LAN have significantly increased body mass and reduced glucose tolerance compared with mice in a standard (LD) light/dark cycle, despite equivalent levels of caloric intake and total daily activity output. Furthermore, the timing of food consumption by DM and LL mice differs from that in LD mice. Nocturnal rodents typically eat substantially more food at night; however, DM mice consume 55.5% of their food during the light phase, as compared with 36.5% in LD mice. Restricting food consumption to the active phase in DM mice prevents body mass gain. These results suggest that low levels of light at night disrupt the timing of food intake and other metabolic signals, leading to excess weight gain. These data are relevant to the coincidence between increasing use of light at night and obesity in humans.
全球肥胖和代谢紊乱的患病率增加，与夜间光照（LAN）和轮班工作的增加同时发生。能量稳态的昼夜节律调节受内源性生物钟控制，生物钟通过光信息同步。为了促进最佳适应功能，生物钟使个体为可预测的事件（如食物供应和睡眠）做好准备，并破坏时钟功能会导致昼夜节律和代谢紊乱。为了确定夜间光照暴露与肥胖之间是否存在因果关系，我们研究了 LAN 对雄性小鼠体重的影响。与在标准（LD）光照/黑暗周期中相比，处于明亮（LL）或昏暗（DM）LAN 中的小鼠的体重明显增加，并且葡萄糖耐量降低，尽管卡路里摄入量和总日活动量相当。此外，DM 和 LL 小鼠的食物消耗时间与 LD 小鼠不同。夜间活动的啮齿动物通常在夜间大量进食；然而，DM 小鼠在光照阶段消耗其食物的 55.5%，而 LD 小鼠则消耗 36.5%。将 DM 小鼠的食物摄入量限制在活动期可防止体重增加。这些结果表明，夜间光照水平低会破坏食物摄入和其他代谢信号的时间安排，导致体重过度增加。这些数据与夜间光照使用增加和人类肥胖的巧合有关。
