Evaluating the therapeutic potential of vagal CART circuitry for treating metabolic disease

摘要 尽管经过几十年的研究，仍然缺乏有效的治疗肥胖的方法。考虑到肥胖的程度 流行病，迫切需要有效减轻体重和维持 减肥.支配肠的迷走神经的结状神经节（NG）神经元是肠神经营养的关键组成部分。 提供负反馈以终止进餐的营养感测机构。餐后信号被感知 通过迷走神经传入终末在肠道和信息被中继中枢神经元的核束 孤形目（NTS）。NG表达的神经肽可卡因和苯丙胺调节转录物（CART） 神经元是控制热量摄入的主要分子信号。在肥胖症中，迷走CART的丧失足以 增加食物摄入量和体重。因此，我们假设在饮食诱导的肥胖中，恢复CART NG神经元中的表达将引起自主减少食物摄入并在体重减轻后维持体重 干预措施。评价靶向CART和支配CART的NG神经元的治疗潜力 （NGCART）我们将研究1）代谢线索如何整合到NGCART神经元中，2）这些信息如何被传递 3）NG神经元中过表达CART对体重的影响。我们将强大的基因 和分子神经科学工具，以迷走神经在体内成像，连接映射，并有针对性地 NGCART神经元中的过度表达。在目标1中，我们建议确定招募NGCART的代谢信号 通过使用注射到CARTCre小鼠的NG中的Cre依赖性病毒示踪剂来绘制神经元的投射， 的NGCART神经元在肠道中的终末，并记录这些神经元在活动物的激活概况，通过使用 一种基因靶向钙指标在目标2中，我们将结合联合收割机多突触电路跟踪与串行二 光子断层扫描以绘制NGCART神经元通过大脑的突触回路。在目标3中，我们将使用cre- 依赖性CART过表达病毒恢复CARTCre小鼠NGCART神经元中的CART表达， 确定饮食诱导的肥胖对进食和体重的影响。这些研究将阐述 以前的工作，通过确定分子和细胞的目标，可以提供基础的发展 治疗肥胖症的外围疗法

ABSTRACT Despite decades of research, effective therapies for obesity are lacking. Given the magnitude of the obesity epidemic, there is a critical need for intervention strategies that effectively reduce body weight and maintain weight loss. Nodose ganglia (NG) neurons of the vagus nerve that innervate the gut are a key component of the nutrient sensing machinery that provides negative feedback to terminate a meal. Postprandial signals are sensed by vagal afferent terminals in the gut and the information is relayed centrally to neurons of the nucleus tractus solitarius (NTS). The neuropeptide cocaine and amphetamine regulated transcript (CART) expressed by NG neurons is a primary molecular signal that controls caloric intake. In obesity, loss of vagal CART is sufficient to increase food intake and body weight. Therefore, we hypothesize that in diet-induced obesity, restoring CART expression in NG neurons will cause voluntary reduction in food intake and sustain body weight after weight loss interventions. To evaluate the therapeutic potential of targeting CART and NG neurons innervating CART (NGCART) we will study 1) how metabolic cues are integrated in NGCART neurons, 2) how this information is relayed centrally, and 3) the impact of overexpressing CART in NG neurons on body weight. We apply powerful genetic and molecular neuroscience tools to the vagus nerve for in vivo imaging, connectivity mapping, and targeted overexpression in NGCART neurons. In aim 1, we propose to determine the metabolic signals that recruit NGCART neurons by using a Cre-dependent viral tracer injected into the NG of CARTCre mice to map the projections and terminals of NGCART neurons in the gut, and record the activation profile of these neurons in live animals by using a genetically targeted calcium indicator. In aim 2, we will combine multisynaptic circuitry tracing with serial two photon tomography to map NGCART neurons synaptic circuitry through the brain. In aim 3, we will use a cre- dependent CART overexpression virus to restore CART expression in NGCART neurons of CARTCre mice and determine the impact on feeding and body weight in diet induced obesity. These studies will elaborate on previous work by identifying a molecular and cellular target that can provide the foundation for developing peripheral treatments for obesity.