Physiological Substrates of a Circadian Oscillator

描述(申请人摘要)：我们的目标是了解机械原理 由此相互作用的化学信使将光信息从 眼睛通过视网膜下丘脑束(RHT)到生物钟在 视交叉上核(SCN)这一过程将光信息从 外部光在内部状态的上下文中。根据目前的奖项，我们 发现来自RHT的化学信号比 之前的想法是。垂体腺苷环化酶激活肽(PACAP)和 谷氨酸(Glu)共定位于视网膜神经节细胞终末 支配着SCN。我们发现了体内功能相互作用的证据 在体外：在夜间，PACAP增强了Glu诱导的SCN的时相延迟 在深夜，它阻断了谷氨酸诱导的时相推进。因此， 对这些信号的响应依赖于状态并受时钟控制。何以 PACAP与Glu相互作用以编码SCN上的光信号？什么蜂窝 过程集成组合信令事件以调制幅度和 清晨和深夜的相位重置方向是否不同？我们会 评估PACAP和Glu在光信号转导过程中的作用和相互作用 活体、从RHT释放、信号转导(S)及其后续分子 早间和深夜发生的事件。需要检验的假设是：1)光 信号包含谷氨酸和PACAP能成分，它们相互作用产生 时钟相位的分级变化，以及2)时钟对PACAP和Glu的响应 由于时钟门控的不同影响而导致的早晚变化 CAMP/PKA信号和分子时钟的状态。多指标 将测量的变化：行为节律，SCN神经元的振荡 在啮齿动物模型中，可能的时钟元素的活性和水平/定位。 这种多学科方法将提供对经典(GLU)和 调节性(PACAP)神经传递、细胞和分子机制 信号整合，以及改变神经元状态的决策过程。 这些都是神经科学中的基本问题。信号转导是一种细胞 过程，并通过识别相关的神经递质、受体，第二 信使系统和目标，我们将能够了解原因 调节时钟中差异状态变化的机制。这项研究 是理解大脑综合功能的基础。它应用了关联性 用于药物时间疗法的策略，并将促进开发 对时序障碍的合理治疗，包括内部 失同步化表现为睡眠、认知和睡眠的紊乱模式 自主神经功能，衰老和抑郁状态下的神经损害。

DESCRIPTION (applicant's abstract): Our objective is to understand mechanisms whereby interacting chemical messengers transduce light information from the eye via the retinohypothalamic tract (RHT) to the circadian clock in the suprachiasmatic nucleus (SCN). This process decodes photic information from external light in the context of internal state. Under the present award, we discovered that the chemical signal from the RHT is more complex than previously thought. Pituitary adenyl cyclase-activating peptide (PACAP) and glutamate (Glu) co-localize within terminals of retinal ganglion cells innervating the SCN. We found evidence for functional interaction both in vivo and in vitro: in early night, PACAP potentiated Glu-induced phase delay of SCN rhythms, while in late night it blocked Glu-induced phase advance. Thus, responses to these signals are state-dependent and clock-controlled. How does PACAP interact with Glu to encode light signals at the SCN? What cellular processes integrate combinatorial signaling events to modulate amplitude and direction of phase resetting differentially in early vs. late night? We will evaluate PACAP and Glu actions and interactions during photic signaling in vivo, release from the RHT, signal transduction(s) and consequent molecular events in early vs. late night. Hypotheses to be tested are that: 1) the light signal contains both Glu- and PACAP-ergic components that interact producing graded changes in clock phase, and 2) the clock's responses to PACAP and Glu change between early and late night due to differential effects of clock-gated cAMP/PKA signaling and the state of the molecular clockworks. Multiple indices of change will be measured: rhythms of behavior, oscillation of SCN neuronal activity, and levels/localizations of putative clock elements in rodent models. This multidisciplinary approach will provide insights into classical (Glu) and modulatory (PACAP) neurotransmission, cellular and molecular mechanisms of signal integration, and decision-making processes that alter neuronal state. These are fundamental issues in neuroscience. Signal transduction is a cellular process, and by identifying the relevant neurotransmitters, receptors, second messenger systems and targets, we will be able to understand the causal mechanisms the mediate differential state changes in the clock. This research is basic to understanding integrative brain function. It has applied relevance for strategies in drug chronotherapeutics and will facilitate developing rationally-based therapies for timing disorders, including internal desynchronizations manifested as disordered patterns of sleep, cognitive and autonomic function, neurological impairment in aging and depressive states.