Cold and hunger induce diurnality in a nocturnal mammal.
Cold and hunger induce diurnality in a nocturnal mammal.
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寒冷和饥饿会导致夜行性哺乳动物的昼夜活动。
DOI：
10.1073/pnas.1413135111
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发表时间：
2014
影响因子：
11.1
通讯作者：
Hut,RoelofA
中科院分区：
文献类型：
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作者：
vanderVinne,Vincent;Riede,SjaakJ;Gorter,JenkeA;Eijer,WillemG;Sellix,MichaelT;Menaker,Michael;Daan,Serge;Pilorz,Violetta;Hut,RoelofA
哺乳动物的昼夜节律系统将日常活动和休息的时间与环境的明暗周期同步。虽然潜在的分子振荡机制已经被很好地研究了，但在日常活动模式(时间生态位转换，时型)中影响表型可塑性的因素目前尚不清楚。分子证据表明，新陈代谢可能会影响昼夜节律分子时钟，但在生物体水平上的证据是缺乏的。在这里，我们展示了寒冷和饥饿对新陈代谢的挑战，在其他情况下会导致夜间活动的小鼠死亡。降低环境温度通过增加白天和减少夜间活动来改变小鼠昼夜昼夜活动的阶段。模拟食物短缺进一步加强了这种影响，它将代谢平衡确定为影响昼夜节律组织的潜在共同因素。CLOCK基因表达分析表明，其潜在的神经机制位于主要的昼夜节律起搏器(下丘脑视交叉上核)的下游或平行，其行为表型伴随着外周组织的时相调整。这些发现表明，夜间活动的哺乳动物可以在昼夜节律组织中表现出相当大的可塑性，并可能在受到能量挑战时采用昼夜表型。我们先前定义的昼夜热能学假说认为，这种昼夜可塑性自然发生在夜间哺乳动物身上，反映了能量平衡的适应性维持。能量消耗的量化表明，自然条件下的昼夜节律降低了老鼠等小型穴居哺乳动物的体温调节成本。因此，对昼夜节律组织的代谢反馈通过减少能量消耗提供了功能上的好处。我们的发现可能有助于阐明人类睡眠-觉醒模式和代谢表型之间的关系。
The mammalian circadian system synchronizes daily timing of activity and rest with the environmental light–dark cycle. Although the underlying molecular oscillatory mechanism is well studied, factors that influence phenotypic plasticity in daily activity patterns (temporal niche switching, chronotype) are presently unknown. Molecular evidence suggests that metabolism may influence the circadian molecular clock, but evidence at the level of the organism is lacking. Here we show that a metabolic challenge by cold and hunger induces diurnality in otherwise nocturnal mice. Lowering ambient temperature changes the phase of circadian light–dark entrainment in mice by increasing daytime and decreasing nighttime activity. This effect is further enhanced by simulated food shortage, which identifies metabolic balance as the underlying common factor influencing circadian organization. Clock gene expression analysis shows that the underlying neuronal mechanism is downstream from or parallel to the main circadian pacemaker (the hypothalamic suprachiasmatic nucleus) and that the behavioral phenotype is accompanied by phase adjustment of peripheral tissues. These findings indicate that nocturnal mammals can display considerable plasticity in circadian organization and may adopt a diurnal phenotype when energetically challenged. Our previously defined circadian thermoenergetics hypothesis proposes that such circadian plasticity, which naturally occurs in nocturnal mammals, reflects adaptive maintenance of energy balance. Quantification of energy expenditure shows that diurnality under natural conditions reduces thermoregulatory costs in small burrowing mammals like mice. Metabolic feedback on circadian organization thus provides functional benefits by reducing energy expenditure. Our findings may help to clarify relationships between sleep–wake patterns and metabolic phenotypes in humans.