Nakamura Wataru, Yamazaki Shin, Takasu Nana N, Mishima Kazuo, Block Gene D
Center for Biological Timing and Department of Biology, University of Virginia, Charlottesville, Virginia 22903-2477, USA.
J Neurosci. 2005 Jun 8;25(23):5481-7. doi: 10.1523/JNEUROSCI.0889-05.2005.
The suprachiasmatic nuclei (SCNs) of the hypothalamus contain a circadian clock that exerts profound control over rhythmic physiology and behavior. The clock consists of multiple autonomous cellular pacemakers distributed throughout the rat SCN. In response to a shift in the light schedule, the SCN rapidly changes phase to achieve the appropriate phase relationship with the shifted light schedule. Through use of a transgenic rat in which rhythmicity in transcription of the Period 1 gene was measured with a luciferase reporter (Per1-luc), we have been successful in tracking the time course of molecular rhythm phase readjustments in different regions of the SCN that occur in response to a shift in the light schedule. We find that different regions of the SCN phase adjust at different rates, leading to transient internal desynchrony in Per1-luc expression among SCN regions. This desynchrony among regions is most pronounced and prolonged when the light schedule is advanced compared with light schedule delays. A similar asymmetry in the speed of phase resetting is observed with locomotor behavior, suggesting that phase shifting kinetics within the SCN may underlay the differences observed in behavioral resetting to advances or delays in the light schedule.
下丘脑的视交叉上核（SCN）含有一个昼夜节律时钟，对节律性生理和行为施加着深远的控制。该时钟由分布在大鼠SCN中的多个自主细胞起搏器组成。响应光照时间表的改变，SCN会迅速改变相位，以与改变后的光照时间表建立适当的相位关系。通过使用一种转基因大鼠，其中用荧光素酶报告基因（Per1-luc）测量Period 1基因转录的节律性，我们成功地追踪了SCN不同区域分子节律相位重新调整的时间进程，这种调整是响应光照时间表的改变而发生的。我们发现，SCN的不同区域以不同的速率进行相位调整，导致SCN区域之间Per1-luc表达出现短暂的内部不同步。与光照时间表延迟相比，当光照时间表提前时，区域间的这种不同步最为明显且持续时间更长。在运动行为中也观察到类似的相位重置速度不对称现象，这表明SCN内的相位移动动力学可能是行为对光照时间表提前或延迟重置中观察到的差异的基础。
