CHOLINERGIC REGULATION OF THE CIRCADIAN CLOCK

描述（改编自申请人的摘要）： 下丘脑的视交叉上核（SCN）产生近24小时的 将行为组织成昼夜节律的时间基础。 中最突出的 由SCN控制的节律是睡眠和觉醒的每日循环。 脑干和基底前脑的胆碱能神经元， 有助于睡眠/觉醒状态，反过来，直接投射到SCN， 提供一个反馈途径，以调节 SCN中的生物钟及其作用的功能背景。 PI对大鼠SCN脑切片制备的广泛研究 建立了这种生物钟经历自发的昼夜节律， 振荡的SCN神经元活动和伴随的调制 对相位重置刺激的敏感性。 通过监测活动节奏 在体外恒定条件下，SCN神经元的整体， 研究人员已经证明，SCN时钟调节自己的时钟， 对传入信号的敏感性 敏感性的昼夜节律模式 与一天的环境周期中的离散时段相关， 晚上 他们发现，生物钟特别敏感 到强大的相位提前毒蕈碱胆碱能刺激期间 在晚上，但不是在白天。 此外，夜间胆碱能 刺激物通过M1样毒蕈碱胆碱能受体起作用以激活 促进计时机制的细胞cGMP途径。 Yhe 研究者建议使用电生理学、生物化学和 免疫细胞化学技术来探讨乙酰胆碱 调节夜间的生物钟 具体目标包括：（1） 阐明了信号转导级联的要素， 胆碱能信号重置SCN计时机制; 2）评估 通过该途径介导的转录激活;和3）定位 细胞成分和变化部位。 这些实验将提供 对中枢毒蕈碱机制的新见解，cGMP/PKG的影响 激活细胞状态，以及大脑调节位点之间的相互作用 睡眠/觉醒和生物钟。 这项研究具有基础 与理解细胞和分子底物的相关性 昼夜节律和睡眠。 它适用于开发 药物时间治疗和改善内部 表现为睡眠紊乱和荷尔蒙模式的去睡眠化， 抑郁性情感障碍，和认知损害（例如，SDAT）由于 胆碱能系统随年龄增长而衰退。

DESCRIPTION (adapted from applicant's abstract): The biological clock in the suprachiasmatic nucleus (SCN) of the hypothalamus generates a near 24-h time base that organizes behaviors into circadian rhythms. Prominent among the rhythms governed by the SCN is the daily cycle of sleep and wakefulness. Cholinergic neurons of the brainstem and basal forebrain, regions that contribute to sleep/arousal states, in turn, project directly to the SCN, providing a route for feedback to the mechanisms that regulate the biological clock in the SCN and the functional contexts in which they act. The PI's extensive studies of the SCN brain slice preparation from rat have established that this circadian clock undergoes spontaneous circadian oscillation in SCN neuronal activity and concomitant modulation of sensitivities to phase-resetting stimuli. By monitoring the activity rhythm of the ensemble of SCN neurons under constant condition in vitro, the investigators have demonstrated that the SCN clock regulates its own sensitivity to afferent signals. The circadian pattern of sensitivities correlates with discrete periods in the environmental cycle of day and night. They have found that the circadian clock is specifically sensitive to robust phase advance by muscarinic cholinergic stimulation during subjective night, but not in the day. Further, nocturnal cholinergic stimuli act via an M1-like muscarinic cholinergic receptor to activate cellular cGMP pathways that advance the timekeeping mechanism. Yhe investigoators propose to use electrophysiological, biochemical and immunocytochemical techniques to probe the mechanism by which acetylcholine regulates the circadian clock at night. Specific aims include: 1) To elucidate the elements of the signal transduction cascade by which nocturnal cholinergic signals reset the SCN timekeeping mechanism; 2) To evaluate transcriptional activation mediated via this pathway; and 3) To localize the cellular constituents and sites of change. These experiments will provide new insights into central muscarinic mechanisms, the effects of cGMP/PKG activation on cell state, and interactions between brain sites regulating sleep/wakefulness and the biological clock. This research has basic relevance to understanding cellular and molecular substrates of both circadian rhythms and sleep. It has applied relevance for developing strategies for drug chronotherapeutics and for ameliorating internal desynchronization manifested as disordered sleep and hormonal patterns, depressive affective disorders, and cognitive impairment (e.g., SDAT) due to decline of the cholinergic system with aging.