van Esseveldt K E, Lehman M N, Boer G J
Graduate School Neurosciences Amsterdam, Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ ZO, Amsterdam, The Netherlands.
Brain Res Brain Res Rev. 2000 Aug;33(1):34-77. doi: 10.1016/s0165-0173(00)00025-4.
Many physiological and behavioral processes show circadian rhythms which are generated by an internal time-keeping system, the biological clock. In rodents, evidence from a variety of studies has shown the suprachiasmatic nucleus (SCN) to be the site of the master pacemaker controlling circadian rhythms. The clock of the SCN oscillates with a near 24-h period but is entrained to solar day/night rhythm by light. Much progress has been made recently in understanding the mechanisms of the circadian system of the SCN, its inputs for entrainment and its outputs for transfer of the rhythm to the rest of the brain. The present review summarizes these new developments concerning the properties of the SCN and the mechanisms of circadian time-keeping. First, we will summarize data concerning the anatomical and physiological organization of the SCN, including the roles of SCN neuropeptide/neurotransmitter systems, and our current knowledge of SCN input and output pathways. Second, we will discuss SCN transplantation studies and how they have contributed to knowledge of the intrinsic properties of the SCN, communication between the SCN and its targets, and age-related changes in the circadian system. Third, recent findings concerning the genes and molecules involved in the intrinsic pacemaker mechanisms of insect and mammalian clocks will be reviewed. Finally, we will discuss exciting new possibilities concerning the use of viral vector-mediated gene transfer as an approach to investigate mechanisms of circadian time-keeping.
许多生理和行为过程都表现出昼夜节律，这些节律由一个内部计时系统——生物钟产生。在啮齿动物中，大量研究证据表明，视交叉上核（SCN）是控制昼夜节律的主起搏器所在部位。SCN的生物钟以近24小时的周期振荡，但会被光调节至太阳日/夜节律。最近在理解SCN昼夜节律系统的机制、其用于调节的输入以及其将节律传递至大脑其他部位的输出方面取得了很大进展。本综述总结了关于SCN特性和昼夜计时机制的这些新进展。首先，我们将总结有关SCN解剖和生理组织的数据，包括SCN神经肽/神经递质系统的作用，以及我们目前对SCN输入和输出途径的了解。其次，我们将讨论SCN移植研究及其如何有助于了解SCN的内在特性、SCN与其靶标之间的通信以及昼夜节律系统中与年龄相关的变化。第三，将综述有关昆虫和哺乳动物生物钟内在起搏器机制中涉及的基因和分子的最新发现。最后，我们将讨论使用病毒载体介导的基因转移作为研究昼夜计时机制方法的令人兴奋的新可能性。
