Vansteensel Mariska J, Michel Stephan, Meijer Johanna H
Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Postal zone S5-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Brain Res Rev. 2008 Jun;58(1):18-47. doi: 10.1016/j.brainresrev.2007.10.009. Epub 2007 Nov 1.
In most animal species, a circadian timing system has evolved as a strategy to cope with 24-hour rhythms in the environment. Circadian pacemakers are essential elements of the timing system and have been identified in anatomically discrete locations in animals ranging from insects to mammals. Rhythm generation occurs in single pacemaker neurons and is based on the interacting negative and positive molecular feedback loops. Rhythmicity in behavior and physiology is regulated by neuronal networks in which synchronization or coupling is required to produce coherent output signals. Coupling occurs among individual clock cells within an oscillating tissue, among functionally distinct subregions within the pacemaker, and between central pacemakers and the periphery. Recent evidence indicates that peripheral tissues can influence central pacemakers and contain autonomous circadian oscillators that contribute to the regulation of overt rhythmicity. The data discussed in this review describe coupling and synchronization mechanisms at the cell and tissue levels. By comparing the pacemaker systems of several multicellular animal species (Drosophila, cockroaches, crickets, snails, zebrafish and mammals), we will explore general organizational principles by which the circadian system regulates a 24-hour rhythmicity.
在大多数动物物种中，昼夜节律计时系统已经进化成为一种应对环境中24小时节律的策略。昼夜节律起搏器是计时系统的基本组成部分，在从昆虫到哺乳动物等动物的解剖学离散位置中都已被识别出来。节律产生发生在单个起搏器神经元中，并且基于相互作用的负性和正性分子反馈环。行为和生理的节律性由神经网络调节，在神经网络中需要同步或耦合来产生连贯的输出信号。耦合发生在振荡组织内的单个时钟细胞之间、起搏器内功能不同的子区域之间以及中央起搏器和外周之间。最近的证据表明，外周组织可以影响中央起搏器，并包含自主的昼夜节律振荡器，这些振荡器有助于调节明显的节律性。本综述中讨论的数据描述了细胞和组织水平上的耦合和同步机制。通过比较几种多细胞动物物种（果蝇、蟑螂、蟋蟀、蜗牛、斑马鱼和哺乳动物）的起搏器系统，我们将探索昼夜节律系统调节24小时节律性的一般组织原则。
