IN VITRO INTERACTIONS BETWEEN CIRCADIAN CLOCK AFFERENTS

由内源性生物钟控制的每日或昼夜节律， 与太阳活动周期同步是所有生物体的特征。的 初级哺乳动物生物钟，在视交叉上核（SCN）， 在体外存活，其中可以通过其24小时监测其相 神经元活动的节律。这种节律的相位变化 反映基础时钟的相位变化。在SCN中，相位为 由来自视网膜、膝状体间小叶的传入调制 外侧膝状体核和中缝核。主 这些输入的神经递质是兴奋性氨基酸（可能是 谷氨酸）、神经肽Y（NPY）和γ-氨基丁酸（GABA），以及 5-羟色胺（5-HT）。这些传入神经主要与 含有血管活性肠多肽（VIP）的SCN细胞，并且可能 汇聚到完全相同的细胞上。因此，除了个别 调制时钟相位，很可能这些传入系统影响 彼此影响SCN时钟相位。虽然之前的研究表明 这些传入神经递质中的每一种都可以使SCN发生相移 起搏器，无论是在体内还是体外，当单独应用时， 关于这些输入之间可能的相互作用的信息很少， 更不知道的是， 互动可能会发生。该提案是一项 对SCN时钟相位的传入调制的广泛研究。这些 实验研究1. 5-HT、NPY、GABA、谷氨酸和视神经 当单独应用时，交叉刺激影响体外SCN， 特别地确定A）它们是否以及何时对时钟进行相移，以及 B）当应用时，它们对SCN神经元活性的急性影响是什么 白天和晚上; 2。5-HT、NPY、谷氨酸、GABA和视神经 交叉刺激在SCN中调节彼此的作用，研究 是否将这些刺激一起应用会影响A）彼此的模式， 相移，以及B）它们对SCN放电率的急性影响 细胞 这将是第一次系统地研究 SCN传入体外，因此它应该提供关键信息 关于哺乳动物昼夜节律系统的基本机制。 此外，对SCN昼夜节律的理解增加， 起搏器可以通过外部刺激进行操纵， 我们在缓解与之相关的问题的能力方面取得了进展， 昼夜节律紊乱，包括失眠、嗜睡症和躁狂 抑郁症，以及相关的医疗和性能问题 时差和轮班制

Daily or circadian rhythms controlled by endogenous clocks and synchronized to the solar cycle are characteristic of all organisms. The primary mammalian circadian clock, in the suprachiasmatic nuclei (SCN), survives in vitro where its phase can be monitored through its 24 hr rhythm of neuronal activity. Changes in the phase of this rhythm reliably reflect phase changes in the underlying clock. In the SCN, phase is modulated by afferents from the retina, intergeniculate leaflet of the lateral geniculate nucleus, and raphe nuclei. The primary neurotransmitters for these inputs are an excitatory amino acid (possibly glutamate), neuropeptide Y (NPY) and gamma-aminobutyric acid (GABA), and serotonin (5-HT), respectively. These afferents synapse primarily onto vasoactive intestinal polypeptide (VIP)-containing SCN cells, and possibly converge onto the exact same cells. Thus, in addition to individually modulating clock phase, it is likely that these afferent systems influence each others effects on SCN clock phase. While previous studies indicate that each of these afferent neurotransmitters can phase-shift the SCN pacemaker, both in vivo and in vitro, when applied individually, there is scant information concerning possible interactions between these inputs, and even less is known about the mechanisms through which these interactions might occur. This proposal represents the first phase of a broad investigation into afferent modulation of SCN clock phase. These experiments investigate 1. How 5-HT, NPY, GABA, glutamate, and optic chiasm stimulation affect the SCN in vitro when applied individually, determining in particular A) if and when they phase-shift the clock, and B) what their acute effects on SCN neuronal activity are when applied during the day and night; and 2. How 5-HT, NPY, glutamate, GABA, and optic chiasm stimulation modulate each other's effects in the SCN, investigating whether applying these stimuli together affects A) each other's pattern of phase-shifting, and B) their acute effects on the firing rates of SCN cells. This will be the first systematic investigation of interactions between SCN afferents in vitro, and as such it should provide critical information concerning the basic mechanisms underlying the mammalian circadian system. In addition, the increased understanding of how the SCN circadian pacemaker can be manipulated by external stimuli should produce rapid advances in our ability to alleviate problems that have been linked to circadian rhythm disorders, including sleeplessness, narcolepsy, and manic depression, as well as the medical and performance problems associated with jet lag and shift work schedules.