Challet Etienne, Caldelas Ivette, Graff Caroline, Pévet Paul
Laboratory of Neurobiology of Rhythms, Centre National de la Recherche Scientifique (UMR7518), University Louis Pasteur, Neuroscience Federation (IFR37), 12 rue de l'université, F-67000 Strasbourg, France.
Biol Chem. 2003 May;384(5):711-9. doi: 10.1515/BC.2003.079.
The molecular clockwork in mammals involves various clock genes with specific temporal expression patterns. Synchronization of the master circadian clock located in the suprachiasmatic nucleus (SCN) is accomplished mainly via daily resetting of the phase of the clock by light stimuli. Phase shifting responses to light are correlated with induction of Per1, Per2 and Dec1 expression and a possible reduction of Cry2 expression within SCN cells. The timing of peripheral oscillators is controlled by the SCN when food is available ad libitum. Time of feeding, as modulated by temporal restricted feeding, is a potent 'Zeitgeber' (synchronizer) for peripheral oscillators with only weak synchronizing influence on the SCN clockwork. When restricted feeding is coupled with caloric restriction, however, timing of clock gene expression is altered within the SCN, indicating that the SCN function is sensitive to metabolic cues. The components of the circadian timing system can be differentially synchronized according to distinct, sometimes conflicting, temporal (time of light exposure and feeding) and homeostatic (metabolic) cues.
哺乳动物的分子生物钟机制涉及多种具有特定时间表达模式的生物钟基因。位于视交叉上核（SCN）的主昼夜节律钟的同步主要通过光刺激对生物钟相位的每日重置来实现。对光的相位移动反应与SCN细胞内Per1、Per2和Dec1表达的诱导以及Cry2表达可能的减少相关。当食物随意可得时，外周振荡器的时间由SCN控制。由限时进食调节的进食时间是外周振荡器的一种强大的“授时因子”（同步器），对SCN生物钟机制的同步影响较弱。然而，当限时进食与热量限制相结合时，SCN内生物钟基因表达的时间会发生改变，这表明SCN功能对代谢信号敏感。昼夜节律计时系统的组成部分可以根据不同的、有时相互冲突的时间（光照时间和进食时间）和稳态（代谢）信号进行差异同步。
