Emergence of circadian and photoperiodic system level properties from interactions among pacemaker cells
Emergence of circadian and photoperiodic system level properties from interactions among pacemaker cells
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DOI：
10.1177/0748730408317992
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发表时间：
2008-08-01
影响因子：
3.5
通讯作者：
Daan, Serge
中科院分区：
文献类型：
--
作者：
Beersma, Domien G. M.;van Bunnik, Bram A. D.;Daan, Serge
温带动物的日常行为和生理模式在夏季和冬季之间往往有很大的不同。在哺乳动物中，这可能是视交叉上核（SCN）活动季节性变化的直接结果。本研究的目的是了解这种变化的基础上的起搏神经元之间的相互作用。计算机模拟表明，SCN中起搏细胞之间的相互电激活，结合光引起的细胞电激活，足以解释包括季节变化在内的各种昼夜节律现象。这些现象是：自激，即在没有明-暗周期的情况下昼夜节律性的自发发展;在恒定黑暗中的持续节律性，以及在恒定光中起搏器输出中的昼夜节律性的丧失;对明-暗周期的夹带;具有不同周期的授时因子周期的后效;昼夜模式对日长的调节;对光脉冲的真实相位响应曲线的产生;并且相对独立于光强度的逐日变化。在模型中，细胞亚群在一天中的特定时间是活跃的。这对于利用SCN将特定行为调整到一天中的特定时间具有功能重要性。因此，开关振荡器的网络提供了一个简单而合理的结构，其行为就像一个时钟，可以读出一天中的时间，同时也可以作为一个时钟用于所有季节。
Daily patterns of behavior and physiology in animals in temperate zones often differ substantially between summer and winter. In mammals, this may be a direct consequence of seasonal changes of activity of the suprachiasmatic nucleus (SCN). The purpose of this study was to understand such variation on the basis of the interaction between pacemaker neurons. Computer simulation demonstrates that mutual electrical activation between pacemaker cells in the SCN, in combination with cellular electrical activation by light, is sufficient to explain a variety of circadian phenomena including seasonal changes. These phenomena are: self-excitation, that is, spontaneous development of circadian rhythmicity in the absence of a light-dark cycle; persistent rhythmicity in constant darkness, and loss of circadian rhythmicity in pacemaker output in constant light; entrainment to light-dark cycles; aftereffects of zeitgeber cycles with different periods; adjustment of the circadian patterns to day length; generation of realistic phase response curves to light pulses; and relative independence from day-to-day variation in light intensity. In the model, subsets of cells turn out to be active at specific times of day. This is of functional importance for the exploitation of the SCN to tune specific behavior to specific times of day. Thus, a network of on-off oscillators provides a simple and plausible construct that behaves as a clock with readout for time of day and simultaneously as a clock for all seasons.