Separate oscillating cell groups in mouse suprachiasmatic nucleus couple photoperiodically to the onset and end of daily activity
Separate oscillating cell groups in mouse suprachiasmatic nucleus couple photoperiodically to the onset and end of daily activity
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DOI：
10.1073/pnas.0607713104
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发表时间：
2007-05-01
影响因子：
11.1
通讯作者：
Honma, Ken-ichi
中科院分区：
文献类型：
--
作者：
Inagaki, Natsuko;Honma, Sato;Honma, Ken-ichi
昼夜行为节律的模式是光周期依赖的，突出表现为行为节律和光周期之间的相位关系的守恒。一个由两个独立但相互耦合的昼夜节律振荡器组成的模型被用来解释夜间啮齿动物行为节律的光周期反应：一个晚上振荡器，驱动活动开始和进入黄昏，另一个早晨振荡器，驱动活动结束，进入黎明。生物发光连续测量时钟基因PER1表达的昼夜节律，使我们能够识别小鼠视交叉上核(SCN)中组成不同时相的昼夜振荡的不同振荡细胞群，并对光周期做出不同的反应。在所观察的三个光周期下，后部SCN的昼夜节律振荡被锁相至活动结束。另一方面，前SCN的振荡在活动开始时是锁相的，但在长光周期下呈双峰模式[光暗周期(LD)18：6]。前部SCN的双峰分布反映了早、晚期的两个昼夜节律振荡细胞群。在中光周期(LD12：12)和短光周期(LD6：18)下，前振荡为单峰振荡，而在LD18：6的晚期，前振荡总是滞后于后振荡。LD18：6相差最大，LD6：118相差最小。这些发现表明，SCN中的三个振荡细胞群构成了区域性的昼夜振荡，其中至少有两个参与了行为节律的光周期反应。
The pattern of circadian behavioral rhythms is photoperiod-dependent, highlighted by the conservation of a phase relation between the behavioral rhythm and photoperiod. A model of two separate, but mutually coupled, circadian oscillators has been proposed to explain photoperiodic responses of behavioral rhythm in nocturnal rodents: an evening oscillator, which drives the activity onset and entrains to dusk, and a morning oscillator, which drives the end of activity and entrains to dawn. Continuous measurement of circadian rhythms in clock gene Per1 expression by a bioluminescence reporter enabled us to identify the separate oscillating cell groups in the mouse suprachiasmatic nucleus (SCN), which composed circadian oscillations of different phases and responded to photoperiods differentially. The circadian oscillation in the posterior SCN was phase-locked to the end of activity under three photoperiods examined. On the other hand, the oscillation in the anterior SCN was phase-locked to the onset of activity but showed a bimodal pattern under a long photoperiod [light-dark cycle (LD)18:6]. The bimodality in the anterior SCN reflected two circadian oscillatory cell groups of early and late phases. The anterior oscillation was unimodal under intermediate (LD12:12) and short (LD6:18) photoperiods, which was always phase-lagged behind the posterior oscillation when the late phase in LD18:6 was taken. The phase difference was largest in LD1 8:6 and smallest in LD6:118. These findings indicate that three oscillating cell groups in the SCN constitute regionally specific circadian oscillations, and at least two of them are involved in photoperiodic response of behavioral rhythm.