Role of Lateral Hypothalamic Leptin Receptor-Neurotensin Neurons in Energy Balanc

描述(申请人提供)：与肥胖相关的(2型)糖尿病会造成巨大的健康损失，但几乎没有改变疾病的治疗方法来阻止这种“糖尿病流行”。需要更好地了解调节能量动态平衡的机制，以确定治疗干预的潜在途径。脂肪衍生的激素瘦素通过大脑中表达长型瘦素受体(LepRb)的神经元发挥作用，减少食物的摄入量，增加能量消耗。瘦素通过下丘脑内侧基底核的LepRb神经元发挥作用的许多方面已经被表征，但它们不能解释瘦素调节食物刺激突显的能力。瘦素作用的一个潜在部位是下丘脑外侧核(LHA)，它含有食欲素(OX)神经元，投射到并调节中脑边缘多巴胺(DA)系统，以改变动机行为(包括食物摄入量和活动)。我在马丁·迈尔斯博士的实验室里的工作已经开始描述LHA LepRb神经元的特征，包括一个与OX神经元分离但与之突触相连的亚群。LHA LepRb神经元的这一亚群共同表达相反的递质：抑制性神经递质GABA和兴奋性神经肽神经降压素(NTS)，神经降压素是中脑边缘多巴胺(DA)系统的已知调节因子；因此我们将这一群体称为LHA LepRbNts神经元。我推测，来自LHA LepRbNts神经元的相反的GABA和NTS信号在能量稳态中介导了不同的调节作用，特别是通过中脑边缘DA系统。在K99指导阶段，我将在NTS信号为零的小鼠(Aim 1)中探索这一假说，同时开发一种新的小鼠模型(NtsFRT Neo-Cre小鼠)，以选择性地识别LHA LepRbNts神经元(Aim 2a)，从而允许对它们的功能进行询问。迈尔斯博士在创造新的小鼠品系方面有着丰富的记录，他在K99阶段的指导对我学习创造NtsFRT Neo-CRE小鼠(以及随后的新小鼠模型)所需的分子遗传学技能至关重要，这些技能将用于我的独立研究计划。在R00阶段，我将杂交NtsFRT Neo-Cre小鼠和现有的小鼠模型，产生选择性地消融所有LHA LepRbNts神经元(Aim 2)或它们的GABA信号(Aim 3)的小鼠，以确定这些神经元的整体作用，并解析GABA在能量稳态中的特定作用。总的来说，指导K99阶段的科学和职业培训方面将提供工具，以建立我在R00阶段的独立研究计划，支持我过渡到肥胖领域富有成效的研究教员职位。总体而言，这一系列研究将确定LHA LepRbNts神经元促进能量稳态的信号机制，以及它们在肥胖发病机制中的作用 公共卫生相关性：肥胖相关的糖尿病是一个日益严重的世界性健康问题，但对调节食物摄入量和体重的系统的了解有限，阻碍了该疾病有效治疗方法的开发。这里的研究将探讨下丘脑外侧区一组独特的神经元调节食物摄入量、体重、活动水平和享乐性或“渴望”反应的机制。这项工作将增加我们对肥胖发展的理解，对这些新神经元的表征可能会找到治疗肥胖症的治疗干预部位。

DESCRIPTION (provided by applicant): Obesity-linked (type-2) diabetes exacts a significant health toll, but there are few disease-modifying treatments to stem this "diabesity epidemic." Better understanding of the mechanisms that regulate energy homeostasis are needed to identify potential pathways for therapeutic intervention. The adipose-derived hormone leptin acts via neurons in the brain that express the long form of the leptin receptor (LepRb) to decrease food intake and potentiate energy expenditure. Many aspects of leptin action via LepRb neurons of the medialbasal hypothalamus have been characterized, but they do not account for leptin's ability to modulate the incentive salience of food. A potential locus for this aspect of leptin action is the lateral hypothalamus (LHA), which contains Orexin (OX) neurons that project to and regulate the mesolimbic dopamine (DA) system to alter motivated behavior (including food intake and activity). My work in the laboratory of Dr. Martin Myers has begun to characterize LHA LepRb neurons, including a subpopulation that are discrete from, but synaptically connected with, OX neurons. This subpopulation of LHA LepRb neurons co-express opposing transmitters: the inhibitory neurotransmitter GABA and the excitatory neuropeptide neurotensin (Nts), a known regulator of the mesolimbic dopamine (DA) system; we therefore refer to this population as LHA LepRbNts neurons. I hypothesize that opposing GABA and Nts signaling from LHA LepRbNts neurons mediate distinct regulatory effects in energy homeostasis, particularly via the mesolimbic DA system. During the K99 mentored phase, I will explore this hypothesis in mice null for Nts signaling (Aim 1) while developing a novel mouse model (NtsFRT Neo-Cre mice) to selectively identify LHA LepRbNts neurons (Aim 2a) allowing for their functional interrogation. Dr. Myers has a substantial track record in creating novel mouse lines, and his mentorship during the K99 phase is essential for my ability to learn the molecular genetics skills necessary to create the NtsFRT Neo-Cre mice (and subsequent novel mouse models) that will be utilized for my independent research program. During the R00 phase, I will interbreed NtsFRT Neo-Cre mice and existing mouse models to generate mice that either selectively ablate all LHA LepRbNts neurons (Aim 2) or their GABA signaling (Aim 3) to identify the roles of these neurons overall and parse the specific role of GABA in energy homeostasis. Collectively, the scientific and career training facets of the mentored K99 phase will provide the tools to establish my independent research program in the R00 phase, supporting my transition to a productive research faculty position in the field of obesity. Overall, this line of research will determine the signaling mechanisms by which LHA LepRbNts neurons contribute to energy homeostasis, and their role in the pathogenesis of obesity PUBLIC HEALTH RELEVANCE: Obesity-linked diabetes is an increasing worldwide health problem, but limited understanding of the systems that regulate food intake and weight has hindered development of effective therapies for this disease. The studies herein will investigate the mechanisms by which a unique group of neurons in the lateral hypothalamus regulate food intake, weight, activity levels and hedonic or "craving" responses. This work will add to our understanding of the development of obesity, and characterization of these novel neurons may identify therapeutic intervention sites for treating obesity.