Integration of circadian and homeostatic signals in a peptidergic circuit in Drosophila

项目摘要/摘要 迅速积累的证据表明，睡眠、活动和进食的昼夜节律模式的中断会导致 对健康有害的后果。虽然生物钟机制已经被很好地研究了，但它们之间的关系 在一天中的时间暗示和饥饿等动态平衡驱动之间，人们对此知之甚少。整合了 含有营养线索的昼夜节律信息发生在大脑核心时钟细胞下游的 多个行为回路的交叉点。这项提议利用了果蝇的黑腹果蝇基因 模型来研究昼夜节律信号与馈电电路整合的机制 协调运动节奏和进食行为。果蝇大脑间部(PI)，类似于 哺乳动物的下丘脑，是一个接受时间和营养状态的肽能中枢。 信息。根据已发表的和初步的研究结果，PI很可能从 通过神经肽信号的核心时钟神经元，以及胆碱能Hugin产生的抑制输入 味觉中间神经元。这一建议的中心假设是每个肽能PI种群 (DH44+，胰岛素样肽生产，SIF酰胺+和桃铁)收到一组独特的输入，然后必须 被整合到PI中以协调行为输出，并且这种整合通过PI内旁分泌进行 神经肽信号。因此，PI种群可能同时调节休息：活动节律和摄食行为 根据营养状态，允许对急性环境提示做出反应。在本课程的指导阶段 项目申请者将描述中央大脑时钟(目标1)和Hugin+的连接性 味觉中间神经元(目标2)至PI，并研究每个回路如何调节摄食和 休息：活动行为(目标1和2)。在这个项目的独立阶段，申请者将使用所获得的技能 在指导阶段，研究饥饿如何超过PI神经元生理和行为的时钟控制 (目标3)以及PI内部连接在协调运动节律和摄食行为方面的作用(目标4)。至 为了实现这些目标，申请者将使用包括RNAi和CRISPR在内的遗传工具的组合， 包括电生理学和钙质成像在内的生理测试，以及用于运动的行为测试 节律和进食。该项目的成功完成将在以下两个层面上取得重要进展 神经回路和行为。首先，它将开始阐明交叉电路如何使用 神经调节多肽。神经调节信号已被证明很难在哺乳动物系统中进行研究，而且 这项工作可以为哺乳动物神经肽能区的研究提供可应用的见解，特别是 在下丘脑。第二，它将促进对昼夜节律和 在回路和行为两个层面上都在进食。不仅了解电路如何塑造行为，而且了解电路如何塑造行为 行为，如改变的进食模式反馈给大脑，对于制定干预措施非常重要 改善人类健康。

Project Summary/ Abstract There is rapidly accumulating evidence that disruptions of circadian patterns of sleep, activity and feeding lead to deleterious health consequences. While circadian clock mechanisms are well-studied, the relationship between time-of-day cues and homeostatic drives such as hunger are poorly understood. The integration of circadian information with nutritional cues occurs downstream of the core clock cells in the brain at the intersection of multiple behavioral circuits. This proposal exploits the Drosophila melanogaster genetic model to examine the mechanism by which circadian signals integrate with feeding circuitry to coordinate locomotor rhythms with feeding behavior. The Drosophila pars intercerebralis (PI), an analog of the mammalian hypothalamus, is a peptidergic center that receives both time-of-day and nutritional state information. Based on published and preliminary findings, it is likely that that the PI receives excitatory input from core clock neurons via neuropeptide signals, as well as inhibitory inputs from cholinergic Hugin-producing gustatory interneurons. The central hypothesis of this proposal is that each of the peptidergic PI populations (DH44+, insulin-like peptide producing, SIFamide+ and Taotie) receives a unique set of inputs, which must then be integrated within the PI to coordinate behavioral outputs, and that this integration occurs via intra-PI paracrine neuropeptide signaling. Thus, PI populations likely modulate both rest:activity rhythms and feeding behavior depending on nutritional state to allow responses to acute environmental cues. In the mentored phase of this project the applicant will characterize the connectivity from the central brain clock (Aim 1) and the hugin+ gustatory interneurons (Aim 2) to the PI and examine how each of these circuits modulates feeding and rest:activity behavior (Aims 1 and 2). In the independent phase of this project the applicant will use skills gained in the mentored phase to investigate how starvation overrides clock control of PI neuron physiology and behavior (Aim 3) and the role of intra-PI connectivity in coordinating locomotor rhythms and feeding behavior (Aim 4). To pursue these aims the applicant will use a combination of genetic tools including RNAi and CRISPR, physiological assays including electrophysiology and calcium imaging, and behavioral assays for locomotor rhythms and feeding. Successful completion of this project will offer important advances at both the level of neural circuitry and behavior. First, it will begin to elucidate how intersecting circuits communicate using neuromodulatory peptides. Neuromodulatory signaling has proven difficult to study in mammalian systems, and this work can offer insights that will be applicable to studies of neuropeptidergic regions in mammals, particularly in the hypothalamus. Second, it will advance understanding of the complex interplay of circadian rhythms and feeding both at the circuit and behavioral levels. Understanding not only how circuitry shapes behavior, but how behavior such as altered feeding patterns feeds back to the brain is important for developing interventions to improve human health.