Identifying the source of feed-forward appetite regulation

项目摘要 饥饿是由位于下丘脑一个独特区域的一组神经元调节的， 核（ARC）。ARC内的Agouti-related peptide（AgRP）神经元在热量缺乏时变得活跃。 当动物的热量充足时，它们会变得不那么活跃。传统上，饥饿被视为 由来自身体外围系统的反馈机制控制，例如循环激素， 表示热量不足。现在已知，除了ARCAgRP神经元被反馈调节之外， ARCAgRP神经元也受到前馈机制的快速调节，如环境 预期摄入的线索。这些前馈机制之一是由突触前抑制 下丘脑腹侧背内侧（vDMH）中存在的神经元，在出现ARCAgRP活性时迅速抑制ARCAgRP活性 食物提示演示。然而，目前还不清楚食物线索的感官检测如何收敛到 下丘脑我假设vDMH的突触前传入是前馈控制的来源， 是食欲调节的基础。 在这个建议中，我将确定下丘脑的高阶输入，这是需要的。 前馈调节vDMH，并最终，ARCAgRP神经元。我会用逆行单突触 追踪技术以识别vDMH的突触前来源。然后，我将确认这些输入是 通过用ChR 2辅助的电路映射表征其突触输入的性质来实现功能。最后要 使用选择性抑制研究和体内钙记录的组合方法来研究 候选输入是快速调节vDMH神经元食物提示反应所必需的。 在这个建议的任期内，我将接受光遗传学、显微镜学、病毒学、计算机 编程、光纤光度测量和来自该领域专家的体内电生理技术。这些 技术和技能将使我能够成功地完成拟议的实验目标，并为我做好准备。 作为一名独立调查员

Project Summary Hunger is regulated by a group of neurons located in a distinct area of the hypothalamus, the arcuate nucleus (ARC). Agouti-related peptide (AgRP) neurons within the ARC become active in a calorically deficient state and become less active when animals are calorically replete. Hunger has traditionally been viewed to be controlled by feedback mechanisms from peripheral systems in the body such as circulating hormones that signal caloric deficiency. It is now known that in addition to ARCAgRP neurons being regulated by feedback mechanisms, ARCAgRP neurons are also rapidly regulated by feedforward mechanisms such as environmental cues that anticipate ingestion. One of these feedforward mechanisms is driven by a presynaptic inhibitory neuron present in the ventral dorsal medial hypothalamus (vDMH) that rapidly inhibits ARCAgRP activity upon food-cue presentations. However, it is unknown how sensory detection of food-cues converge on to the hypothalamus. I hypothesize that presynaptic afferents to the vDMH are the source of feedforward control and is the basis of appetite regulation. In this proposal, I will identify the higher-order inputs to the hypothalamus that are required for the feedforward regulation of the vDMH, and ultimately, ARCAgRP neurons. I will use retrograde monosynaptic tracing techniques to identify the presynaptic sources to the vDMH. I will then confirm that these inputs are functional by characterizing the nature of their synaptic input with ChR2-assisted circuit mapping. Finally, I will use a combinatorial approach of selective inhibition studies and in vivo calcium recordings to study if the candidate input is required for the rapid regulation of vDMH neuronal food-cue responses. During the tenure of this proposal, I will receive training in optogenetics, microscopy, virology, computer programming, fiber-photometry, and in vivo electrophysiological techniques from experts in the field. These techniques and skills will allow me to successfully complete the proposed experimental aims and prepare me for a career as an independent investigator.