Neuropeptides and the Mammalian Circadian System

神经肽和哺乳动物昼夜节律系统

• 批准号: 7008133
• 负责人: CHRISTOPHER SCOTT COLWELL
• 金额: $ 35.16万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7008133
• 关键词: biological signal transduction; calcium flux; circadian rhythms; electrophysiology; gene expression; genetically modified animals; glutamates; immunocytochemistry; in situ hybridization; laboratory mouse; membrane potentials; neuropeptides; polymerase chain reaction; protooncogene; suprachiasmatic nucleus; vasoactive intestinal peptide; voltage /patch clamp; voltage gated channel

DESCRIPTION (provided by applicant): Our long-term goal is to understand the mechanisms by which environmental signals regulate circadian oscillators as well as how circadian oscillators are coupled to each other, using neurons in the rodent suprachiasmatic nucleus (SCN) as a model system. A variety of evidence suggests that glutamate plays a critical role in the transmission of photic information from the environment to the SCN and that the peptide PACAP is a co-transmitter with glutamate at the RHT/SCN synaptic connection. A major goal of this application is to understand the mechanisms by which PACAP modulates glutamate-induced signaling in SCN neurons. We will present data indicating that PACAP enhances AMPA currents in SCN neurons from mice. Furthermore, data from a new line of transgenic animals in which the PACAP gene has been inactivated demonstrate a reduction in the magnitude of the effects of light on the circadian system. Thus, we feel confident that both glutamate and PACAP play a role, be it as yet undetermined, in mediating the effects of light on the circadian system. Many of the retino-recipient SCN neurons receiving this photic information themselves express the peptide VIP as well as GABA. These SCN cells synapse largely onto other SCN cells and presumably use these molecules to communicate photic information to other cells in the SCN. Thus, a second goal is to understand the mechanisms by which VIP modulates GABA-induced signaling pathways in SCN neurons. For this project, we will present data consistent with our hypothesis that VIP acts to modulate GABA currents in SCN neurons in mice. Encouragingly, data from a new line of transgenic animals in which the VIP gene has been inactivated demonstrate major disruptions in the circadian system that are consistent with VIP's role as a coupling agent within the SCN. By carrying out this research, we will address important questions about how SCN cells are coupled to the environment as well as how SCN cells are coupled to each other. In addition, we hope to use the SCN as model system to better understand the role of peptide co-transmitters in mediating cell-to-cell communication. These questions will be addressed using electrophysiological and calcium imaging techniques on SCN neurons in a mouse brain slice preparation. In addition, transgenic mice lacking PACAP and VIP will be analyzed with behavioral and anatomical tools. These newly developed mice are likely to prove a useful tool for circadian rhythms research.

描述（由申请人提供）：我们的长期目标是使用啮齿动物视交叉上核（SCN）中的神经元作为模型系统，了解环境信号调节昼夜节律振荡器的机制以及昼夜节律振荡器如何相互耦合。多种证据表明，谷氨酸在光信息从环境到 SCN 的传递中发挥着关键作用，并且肽 PACAP 是 RHT/SCN 突触连接处谷氨酸的共同递质。该应用的一个主要目标是了解 PACAP 调节 SCN 神经元中谷氨酸诱导的信号传导的机制。我们将提供表明 PACAP 增强小鼠 SCN 神经元中 AMPA 电流的数据。此外，来自 PACAP 基因已失活的新转基因动物品系的数据表明，光对昼夜节律系统的影响程度有所降低。因此，我们相信谷氨酸和 PACAP 在调节光对昼夜节律系统的影响方面都发挥着一定的作用，尽管这一作用尚未确定。许多接收光信息的视网膜受体 SCN 神经元本身表达肽 VIP 和 GABA。这些 SCN 细胞主要突触到其他 SCN 细胞上，并且可能使用这些分子将光信息传递给 SCN 中的其他细胞。因此，第二个目标是了解 VIP 调节 SCN 神经元中 GABA 诱导的信号通路的机制。对于这个项目，我们将提供与我们的假设一致的数据，即 VIP 可以调节小鼠 SCN 神经元中的 GABA 电流。令人鼓舞的是，来自 VIP 基因已失活的新转基因动物品系的数据表明，昼夜节律系统受到重大破坏，这与 VIP 作为 SCN 内偶联剂的作用一致。通过开展这项研究，我们将解决有关 SCN 细胞如何与环境耦合以及 SCN 细胞如何相互耦合的重要问题。此外，我们希望使用SCN作为模型系统来更好地理解肽协同递质在介导细胞间通讯中的作用。这些问题将通过对小鼠大脑切片制备中的 SCN 神经元使用电生理学和钙成像技术来解决。此外，将使用行为和解剖工具对缺乏 PACAP 和 VIP 的转基因小鼠进行分析。这些新开发的小鼠很可能成为昼夜节律研究的有用工具。