Integration of Peripheral and Central Appetite Signals by Brainstem Neurons

描述（由申请人提供）：肥胖是美国的一个主要健康问题，是心血管疾病、糖尿病和中风的主要原因。肥胖研究中一个不太清楚的领域是神经元对有关能量状态的中枢和外周信号的反应、整合和传递机制，以及这些信号通路在肥胖中如何改变。我们的长期目标是了解脑干孤束核（NTS）神经元控制体重的分子和细胞机制，以及这些机制在肥胖症中如何改变。内脏传入，包括胃传入，携带饱腹感的信息终止于NTS。因此，NTS神经元充当门，决定传入中包含的信息传递到其他大脑区域。切除表达儿茶酚胺的NTS神经元（NTS-CA神经元）会破坏几种激素对食物摄入的控制，包括生长激素释放肽和胆囊收缩素（CCK）。这项建议的总体目标是确定NTS-CA神经元在正常和肥胖条件下对食欲调节输入做出反应的机制。我们的中心假设是，NTS-CA神经元的输出是传入和激素输入的整合，并且它被不同的能量状态改变，例如禁食或肥胖。我们将通过以下三个具体目标来检验这一假设。(1)确定传入输入如何调节NTS-CA神经元。为此，我们的工作假设是，NTS-CA神经元的放电率是由内脏传入，包括胃传入，通过直接和间接的输入控制。(2)确定关键激素食欲调节剂调节NTS-CA神经元的机制。我们的工作假设，这一目标是CCK，抑制食物的摄入量和ghrelin，刺激食物的摄入量，调节NTS-CA神经元的输出。(3)确定NTS-CA神经元如何适应不同的能量状态。我们的工作假设是，NTS-CA神经元适应长期暴露于激素或改变能量状态的条件。我们已经做好了充分的准备进行拟议的研究，因为我们已经开发了一个小鼠水平脑切片，使我们能够选择性地刺激内脏传入，同时使用电生理膜片钳技术从确定的NTS-CA神经元记录。这是一个非常强大的系统，以解决NTS-CA神经元整合神经元和激素反应的细胞和分子机制，以及这些机制如何在肥胖症中改变。此外，我们将使用标记技术来专门识别接受胃传入输入的NTS-CA神经元，药理学来剖析分子信号传导通路和行为范式来研究这些通路/机制在不同能量状态下如何改变。这项工作的贡献预计将是显着的，因为增加我们对食欲控制的分子机制以及这些机制在不同能量状态下如何改变的理解，将导致更精确的针对性方法用于预防治疗肥胖。公共卫生相关性：这项拟议中的研究与公共卫生有关，因为肥胖是美国的一个主要健康问题，是心血管疾病、糖尿病和中风的主要原因。这些研究的预期贡献将是确定一组关键神经元控制体重调节的分子机制，以及这些机制在肥胖症中是如何改变的。我们相信，增加我们对这些机制的理解将导致更精确的预防和治疗肥胖的靶向方法。

DESCRIPTION (provided by applicant): Obesity is a major health problem in the United States and is a leading contributor to cardiovascular disease, diabetes mellitus and stroke. One of the less well understood areas of obesity research are the mechanisms by which neurons respond to, integrate and pass on central and peripheral signals about energy state and how these signaling pathways are altered in obesity. Our long-range goal is to understand the molecular and cellular mechanisms by which neurons in the nucleus of the solitary tract (NTS) of the brainstem control body- weight and how these mechanisms are altered in obesity. Visceral afferents, including gastric afferents, carrying information about satiety terminate in the NTS. As such, NTS neurons act as gates, determining what information contained in afferents is passed onto other brain regions. Ablation of NTS neurons expressing catecholamines (NTS-CA neurons) disrupts control of food intake by several hormones, including ghrelin and cholecystokinin (CCK). The overall objective of this proposal is to identify the mechanisms by which NTS-CA neurons respond to appetite-regulating inputs under normal and obese conditions. Our central hypothesis is that the output of NTS-CA neurons is an integration of afferent and hormonal inputs and that it is altered by different energy states, such as fasting or obesity. We will test this hypothesis with the following three specific aims. (1) Determine how afferent inputs regulate NTS-CA neurons. Our working hypothesis for this aim is that the firing rate of NTS-CA neurons is controlled by visceral afferents, including gastric afferents, both through direct and indirect inputs. (2) Identify mechanism(s) by which key hormonal appetite modulators regulate NTS- CA neurons. Our working hypothesis for this aim is that CCK, which inhibits food intake and ghrelin, which stimulates food intake, regulate the output of NTS-CA neurons. (3) Determine how NTS-CA neurons adapt to different energy states. Our working hypothesis for this aim is that NTS-CA neurons adapt to prolonged exposure to hormones or conditions of altered energy states. We are well prepared to undertake the proposed research because we have developed a mouse horizontal brain slice that allows us to selectively stimulate visceral afferents while recording from identified NTS-CA neurons using electrophysiological patch clamp techniques. This is an extremely powerful system to address the cellular and molecular mechanisms by which NTS-CA neurons integrate neuronal and hormonal responses and how these mechanisms are altered in obesity. In addition, we will use labeling techniques to specifically identify NTS-CA neurons receiving gastric afferent inputs, pharmacology to dissect out molecular signaling pathways and behavioral paradigms to examine how these pathways/mechanisms are altered in different energy states. The contribution of this work is expected to be significant, because increasing our understanding of the molecular mechanisms underlying appetite control and how these mechanisms are altered in different energy states, will lead to more precisely targeted approaches for the prevention treatment of obesity. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because obesity is a major health problem in the United States and is a leading contributor to cardiovascular disease, diabetes mellitus and stroke. The expected contribution of these studies will be the identification of molecular mechanisms by which one group of critical neurons control weight regulation and how these are altered in obesity. The belief is that increasing our understanding of these mechanisms will lead to more precisely targeted approaches for the prevention and treatment of obesity.