Dissecting the functional organization of the serotonergic system in C. elegans

剖析线虫血清素系统的功能组织

• 批准号: 10334517
• 负责人: Steven Willem Flavell
• 金额: $ 28.97万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-19 至 2024-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10334517
• 关键词: Action Potentials; Afferent Neurons; Animal Behavior; Animal Feed; Animals; Architecture; Aversive Stimulus; Behavior; Behavior Control; Behavioral; Biological Models; Brain; Brain imaging; CRISPR/Cas technology; Caenorhabditis elegans; Calcium; Cells; Circadian Rhythms; Complex; Cues; Data; Desire for food; Drosophila genus; Enteral; Enzymes; Equilibrium; Food; Genes; Genetic; Goals; Human; Image; Immobilization; Ingestion; Invertebrates; Kinetics; Label; Link; Locomotion; Mammals; Maps; Measures; Mediating; Membrane; Membrane Transport Proteins; Monitor; Mutation; Nervous system structure; Neurons; Neurosciences; Optics; Orthologous Gene; Output; Pattern; Pharmaceutical Preparations; Publishing; Satiation; Sensory; Serotonergic System; Serotonin; Signal Transduction; Site; Source; Stimulus; Synapses; System; Technology; Work; behavioral response; cell type; connectome; egg; feeding; genetic approach; imaging approach; in vivo; mind control; neural circuit; optogenetics; raphe nuclei; receptor; receptor expression; receptor function; relating to nervous system; response; serotonin receptor; squid axon; tool

The serotonergic system impacts a wide range of human behaviors and is a common target of psychiatric drugs. In mammals, neural circuits that receive serotonergic inputs are composed of diverse cell types, each of which expresses a subset of 14 distinct serotonin (5-HT) receptors. The impact of 5-HT release on circuit function involves the coordinated activation of many receptor types in distinct neurons. However, we do not yet understand the fundamental principles by which 5-HT acts at many sites within a circuit to coherently alter circuit function. Here, we propose to resolve this question in C. elegans. The C. elegans nervous system is particularly attractive for whole-circuit questions in neuroscience because it consists of exactly 302 neurons, every neuron can be identified in every animal, the synaptic connections between these neurons (the “connectome”) have been fully defined, and excellent genetic tools can be used to manipulate single cells in this well-defined system. Moreover, this animal’s transparency allows us to use cutting-edge imaging approaches – including whole-brain calcium imaging – to monitor neural activity in freely-behaving animals. Importantly, 5-HT signaling is well- conserved from C. elegans to mammals: C. elegans orthologs of human genes encode for 5-HT synthesis enzymes (TPH), vesicular and membrane transporters (VMAT, SERT), 5-HT receptors (5-HT1, 5-HT2, etc) and more. Thus, studies of this animal should reveal general principles of 5-HT function that can be subsequently applied to more complex animals. The studies in this proposal build off recently published work from my lab and new preliminary data. In a recent study, we found that food ingestion by C. elegans activates a specific 5-HTergic neuron, called NSM, whose release of 5-HT drives slow locomotion while animals feed. We also showed that this neuron’s dynamical response to food ingestion controls locomotion dynamics: different patterns of 5-HT release drive different locomotion changes. In new preliminary data, we have systematically examined how patterned 5-HT release impacts locomotion, begun mapping out the 5-HT receptors that mediate these effects, and developed an approach to monitor 5-HT-induced changes in whole-brain activity. In the current proposal, we will use this well-constrained experimental paradigm and these cutting-edge imaging approaches to probe the functional architecture of the 5-HT system and examine how 5-HT receptors interact to control brain function. Specifically, we will first map out the 5-HT receptors and circuits that mediate behavioral responses to different patterns of 5-HT release (Aim 1). In a second aim, we will use new calcium imaging approaches to determine how different patterns of 5-HT release engage different 5-HT receptor types to alter whole-brain activity (Aim 2). Finally, we will also examine how aversive cues that antagonize 5-HT signaling modulate the function of serotonergic circuits, allowing animals to balance aversive and appetitive inputs (Aim 3). These studies will reveal how patterned 5-HT release engages specific 5-HT receptor types to impact brain function, yielding a new framework for 5-HT circuit organization and function.

血清素能系统会影响广泛的人类行为，是精神病的常见目标 毒品。在哺乳动物中，接受血清能输入的神经回路由潜水细胞类型组成，每一种 表达14个不同的5-羟色胺（5-HT）受体的子集。 5-HT释放对电路函数的影响 涉及不同神经元中许多受体类型的协调激活。但是，我们还没有 了解5-HT在电路中的许多站点进行作用以相干改变电路的基本原理 功能。在这里，我们建议在秀丽隐杆线虫中解决这个问题。秀丽隐杆线虫神经系统尤其是 神经科学中的全部电路问题有吸引力，因为它完全由302个神经元组成 可以在每种动物中识别，这些神经元之间的突触连接（“连接”）具有 被充分定义，可以使用出色的遗传工具来操纵这个定义明确的系统中的单个细胞。 此外，这种动物的透明度使我们能够使用尖端的成像方法 - 包括全脑 钙成像 - 监测自由行为动物的神经元活性。重要的是，5-HT信号是很好的 从秀丽隐杆线虫到哺乳动物的保守：人类基因的秀丽隐杆线虫编码为5-HT合成 酶（TPH），囊泡和膜转运蛋白（VMAT，SERT），5-HT接收器（5-HT1、5-HT2等）和 更多的。这是对该动物的研究应揭示5-HT功能的一般原理，随后可以 应用于更复杂的动物。该提案中的研究源于我实验室的最近发表的工作， 新的初步数据。在最近的一项研究中，我们发现秀丽隐杆线虫摄入的食物摄入会激活特定的5次矫正 神经元称为NSM，他的5-HT释放在动物进食时驱动缓慢的运动。我们还表明 这种神经元对食物摄入的动态反应控制了运动动力学：5-HT的不同模式 释放驱动器不同的运动变化。在新的初步数据中，我们系统地检查了 图案化的5-HT释放会影响运动，开始绘制介导这些效果的5-HT接收器， 并开发了一种监测5-HT诱导的全脑活动变化的方法。在当前的提议中 我们将使用这种受约束的实验范式和这些尖端的成像方法来证明 5-HT系统的功能架构并检查了5-HT接收器如何相互作用以控制大脑功能。 具体来说，我们将首先绘制出媒体行为对不同的媒体响应的5-HT接收器和电路 5-HT释放的模式（AIM 1）。在第二个目标中，我们将使用新的钙成像方法来确定 5-HT释放的不同模式如何吸引不同的5-HT受体类型来改变全脑活动（AIM 2）。 最后，我们还将研究如何厌恶5-HT信号传导的厌恶提示调节 血清素能圈，使动物能够平衡厌恶和食欲的输入（AIM 3）。这些研究将揭示 图案化的5-HT释放如何与特定的5-HT接收器类型相关，以影响大脑功能，从而产生新的功能 5-HT电路组织和功能的框架。