Inhibitory Cell Types and Circuits in the Lateral Hypothalamus

项目摘要/摘要 这项建议的目标是定义细胞多样性，连接性和功能的抑制性神经元在 下丘脑外侧区(LHA)。LHA是协调行为基本方面的关键 由于它在多个神经和体液系统的交叉点上的独特位置。LHA GABA能神经元 尤其是作为唤醒、目标导向行为的有力驱动者，以及消极和 正价行为。在这一大类抑制性LHA神经元中，存在着分辨不佳但功能上 重要的亚群，这可能不同地决定行为输出。其中重要的一点是 一群可能的抑制性神经元，表达神经肽黑色素浓缩激素(MCH)。 LHA MCH表达神经元(LHAMCH)表现出显著的功能多样性，发出广泛的投射 整个大脑，并协调广泛的生理功能和行为，包括 调节睡眠-觉醒状态、进食、动机行为、压力和记忆。然而，试验性的 LHAMCH神经元的操作在很大程度上是在LHAMCH神经元是单片的上下文中解释的， 神经调节投射系统，造成了对其功能来源的深刻认识差距 多样性。因此，迫切需要描述独特的细胞、电路和行为影响 LHAMCH多样性。在前一个赠款周期中，我们在实现我们的长期目标方面取得了重大进展 确定LHA GABA能神经元的群体结构，包括Most的产生 到目前为止，小鼠体内分子上不同的LHA细胞类型的全面细胞分类学。在这里，我们将建造 根据这一进展，通过我们的研究：1)两个转录上不同的LHAMCH亚群 神经激肽B受体NK3R的差异表达；2)和一种新的 杏仁中央延长区NKB神经元向LHA投射。在目标1中，我们将确定是否 不同的LHAMCH亚群导致功能子回路投射到大脑中的不同目标和 基于NK3R浓缩的精确交叉病毒策略释放不同的神经化学物质 在一个LHAMCH亚群中高于另一个亚群。在目标2中，我们将探索LHAMCH的差异接触 亚群使用两种平行的交叉策略来引出不同的行为指令 光基因定位LHAMCH亚群，然后让动物接受一系列行为 评估。在目标3中，我们将研究NKB/NK3R信号转导的生物学机制。 中枢延伸杏仁核-LHA环路的详细电生理研究 传递到LHAMCH神经元，并研究这些投射的行为影响。团结在一起， 拟议的实验将解决与细胞和电路级功能有关的悬而未决的问题 LHAMCH神经元多样性，这是从机制上理解LHA电路功能所必需的，以及 作为确定神经精神、睡眠和代谢紊乱治疗靶点的关键前体。

PROJECT SUMMARY/ABSTRACT The goal of this proposal is to define the cellular diversity, connectivity and function of inhibitory neurons in the lateral hypothalamic area (LHA). The LHA is a linchpin in the orchestration of fundamental aspects of behavior owing to its unique position at the intersection of multiple neural and humoral systems. LHA GABAergic neurons in particular have emerged as potent actuators of arousal, goal-directed behavior as well as both negative and positive valence behavior. Within this broad class of inhibitory LHA neurons lie poorly resolved but functionally important subpopulations, which may differentially determine behavioral output. Important among these is a population of putative inhibitory neurons that express the neuropeptide melanin-concentrating hormone (MCH). LHA MCH-expressing neurons (LHAMCH) display remarkable functional diversity, sending extensive projections throughout the brain and coordinating a broad range of physiological functions and behaviors, including the modulation of sleep-wake states, feeding, motivated behavior, stress and memory. However, experimental manipulations of LHAMCH neurons are largely interpreted in the context of LHAMCH neurons being a monolithic, neuromodulatory projection system, creating a profound knowledge gap as to the source of their functional diversity. There is, therefore, a critical need to delineate the unique cellular, circuit-level and behavioral impact of LHAMCH diversity. In the previous grant cycle, we made significant progress towards our long-term goal of defining the population structure of LHA GABAergic neurons, including the generation of the most comprehensive cellular taxonomy to date of molecularly distinct LHA cell types in the mouse. Here, we will build upon that progress through our investigation of: 1) two transcriptomically-distinct LHAMCH subpopulations that differentially express the neurokinin 3 receptor (NK3R), the receptor for neurokinin B (NKB); 2) and a novel projection from NKB neurons in the central extended amygdala to the LHA. In Aim 1, we will determine whether distinct LHAMCH subpopulations give rise to functional sub-circuits that project to different targets in the brain and release different neurochemicals using a precise intersectional viral strategy based on the enrichment of NK3R in one LHAMCH subpopulation over the other. In Aim 2, we will explore whether differential engagement of LHAMCH subpopulations elicits distinct behavioral repertoires using two parallel intersectional strategies for optogenetically targeting LHAMCH subpopulations and then subjecting animals to a suite of behavioral assessments. In Aim 3, we will investigate the biological mechanisms underlying NKB/NK3R signaling in the central extended amygdala–LHA circuit through a detailed electrophysiological investigation of NKB/GABA co- transmission onto LHAMCH neurons, and by studying the behavioral impact of these projections. Together, the proposed experiments will address outstanding questions concerning the cellular and circuit-level functions of LHAMCH neuron diversity, which is necessary both for a mechanistic understanding of LHA circuit function, and as a critical precursor for identifying therapeutic targets for neuropsychiatric, sleep and metabolic disorders.