PHYSIOLOGICAL DISSECTION OF THE SCN

描述（由申请人提供）：视交叉上核（SCN）是大脑时钟的所在地。在细胞水平上，节律性是通过调节各种时钟基因的转录/翻译的基于细胞的负反馈环产生的。虽然近年来我们对基于细胞的振荡器的分子机制的理解有了巨大的进步，但这些振荡器在SCN组织水平上的组织还不太发达。一方面，已经提出所有SCN细胞都是昼夜节律振荡器。另一方面，我们对仓鼠SCN的研究，基于Period mRNA（Per 1，Per 2，Per 3）的表达，表明SCN内有功能不同的隔室;一个包含节律振荡器，另一个包含昼夜节律门控，光响应，非振荡细胞。该组织认为，振荡和夹带信息可能会在SCN内的不同站点集成。这样的观点将改写我们的理解，如相移，夹带，后效等现象，我们建议利用小鼠基因组的解码所提出的进展，以解决SCN组织的问题。在基线研究中，我们描述了昼夜节律和昼夜节律，以及对相位提前和延迟光脉冲的反应，这些反应在一个良好表征的小鼠品系（Aim I）中。初步研究表明，小鼠SCN与仓鼠SCN一样，由两种截然不同的细胞类型组成，这是基于它们的光响应性和振荡特性。为了理解这种昼夜调节系统的组织，我们将使用具有GFP报告基因的转基因动物，GFP报告基因是SCN的节律（Per 1：：GFP）和光诱导（钙结合蛋白：：GFP）区室的标记物（Aim II和III）。最后，我们将使用钙成像和电记录和刺激来表征SCN的微电路，以了解SCN的网络特性，使用GFP来表征所识别的（Per 1：：GFP和CalB：：GFP）SCN细胞类型的响应（Aim IV）。

DESCRIPTION (provided by applicant): The suprachiasmatic nuclei (SCN) are the locus of the brain clock. At the cellular level, rhythmicity is produced by regulation of a cell-based negative feedback loop of transcription/translation of various clock genes. While our understanding of the molecular mechanisms of cell based oscillators has advanced tremendously in recent years, the organization of these oscillators at the level of SCN tissue is less well developed. On the one hand, it has been proposed that all SCN cells are circadian oscillators. On the other hand, our work on hamster SCN, based on Period mRNA (Per1, Per2, Per3) expression, suggests that there are functionally distinct compartments within the SCN; one contains rhythmic oscillators and the other contains circadian-gated, light responsive, non-oscillating cells. This organization suggests that oscillating and entraining information might be integrated at different sites within the SCN. Such a view would rewrite our understanding of such phenomena as phase shifting, entrainment, after-effects, etc.We propose to take advantage of the advances presented by the decoding of the mouse genome, to address questions of SCN organization. In baseline studies, we characterize the circadian and diurnal rhythms, and responses to phase advancing and delaying light pulses in a well characterized mouse strain (Aim I). Pilot studies suggest that the mouse SCN, like that of the hamster is made up of two distinctly different cell types, based on their light responsiveness and oscillating properties. To understand the organization of this circadian regulatory system, we will use transgenic animals with GFP reporters that are markers for the rhythmic (Per1 ::GFP) and light-induced (calbindin::GFP) compartments of the SCN (Aim II and III). Finally, we will characterize the microcircuitry of the SCN using calcium imaging and electrical recording and stimulation to understand the network properties of the SCN, using GFP to characterize the responses of identified (Per1 ::GFP and the CalB::GFP) SCN cell types (Aim IV).