IN VITRO INTERACTIONS BETWEEN CIRCADIAN CLOCK AFFERENTS

每日或昼夜节律由内源性时钟和 与太阳周期同步是所有生物体的特征。这个 哺乳动物的初级生物钟，在视交叉上核(SCN)， 在体外存活，可在24小时内监测其状态 神经元活动的节律。可靠地改变这一节奏的阶段 反映基础时钟中的相位变化。在SCN中，阶段是 受来自视网膜的传入的调制，膝间小叶 外侧膝状核和中缝核团。初级阶段 这些输入的神经递质是一种兴奋性氨基酸(可能 谷氨酸)、神经肽Y(NPY)和γ-氨基丁酸(GABA)，以及 5-羟色胺(5-羟色胺)。这些传入神经元主要通过突触 含有血管活性肠多肽(VIP)的SCN细胞，并可能 汇聚到完全相同的细胞上。因此，除了个别 调制时钟相位，很可能是这些传入系统影响 互为影响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个都可以使SCN相移 无论是体内还是体外起搏器，单独使用时，有 关于这些输入之间可能相互作用的信息很少， 而更少人知道这些是通过什么机制 可能会发生相互作用。这项提案代表了 对SCN时钟相位的传入调制进行了广泛研究。这些 实验研究1.5-羟色胺、神经肽Y、GABA、谷氨酸和视神经 交叉刺激单独应用时会在体外影响SCN， 具体确定A)是否以及何时对时钟进行相移，以及 B)应用时对SCN神经元活动的急性影响是什么？ 2.5-羟色胺、神经肽Y、谷氨酸、GABA和视神经 交叉刺激在SCN中的相互调节作用，研究 这些刺激一起使用是否会影响A)彼此的模式 相移，以及B)它们对SCN的放电率的严重影响 细胞。 这将是对两国之间相互作用的首次系统调查。 SCN在体外传入，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昼夜节律的了解不断增加 起搏器可受外界刺激操纵应迅速产生 我们缓解问题的能力取得了进展，这些问题与 昼夜节律紊乱，包括失眠、嗜睡和躁狂 抑郁症，以及与之相关的医疗和表现问题 时差和倒班工作安排。

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.