CHOLINERGIC REGULATION OF THE CIRCADIAN CLOCK

描述(改编自申请者的摘要)：生物钟 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基。突出的是 由SCN支配的节奏是睡眠和清醒的日常周期。 脑干和基底前脑的胆碱能神经元 有助于睡眠/觉醒状态，进而直接投射到SCN， 提供了一条反馈给监管 SCN中的生物钟及其作用的功能环境。 PI对大鼠SCN脑片制备的广泛研究 建立了这个生物钟经历自发的昼夜节律 SCN神经元活动的振荡及其伴随的调制 对相位重置刺激的敏感性。通过监测活动节律 在体外恒定条件下的SCN神经元集合， 研究人员已经证明，SCN的时钟可以自己调节 对传入信号的敏感性。敏感性的昼夜节律模式 与一天和一天的环境周期中的离散周期相关 晚上好。他们发现生物钟特别敏感。 刺激M胆碱能显著促进时相进展 主观的夜晚，但不是白天。此外，夜间胆碱能 刺激通过类M_1胆碱能受体激活 促进计时机制的细胞内cGMP途径。是的 研究人员建议使用电生理、生化和 免疫细胞化学技术探讨乙酰胆碱的作用机制 调节夜间的生物钟。具体目标包括：1) 阐明信号转导级联的元件，通过它夜间 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；以及3)定位 细胞成分和变化部位。这些实验将提供 对中枢毒扁豆碱机制的新见解，cGMP/PKG的作用 激活对细胞状态的影响以及大脑各部位之间的相互作用 睡眠/清醒和生物钟。这项研究具有基本的 与理解两者的细胞和分子底物的相关性 昼夜节律和睡眠。它具有开发应用的现实意义 药物计时疗法和改善内科疾病的策略 去同步化表现为睡眠紊乱和荷尔蒙模式， 抑郁性情感障碍和认知障碍(例如，SDAT) 胆碱能系统随着年龄的增长而衰退。

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.