Development and Functional Analysis of Components of the Zebrafish Serotonin Sign

描述（申请人提供）：肠神经系统在肠的正常功能中起着至关重要的作用。肠神经元提供运动和感觉信息，以产生推进运动和维持器官稳态。消化系统的内稳态也部分由存在于不同亚型肠内分泌细胞上的化学传感器维持。这些细胞分布在整个肠上皮中，以帮助将腔内条件传递给粘膜下层的肠神经元。肠内分泌细胞分泌多种介质刺激传入神经元。这些细胞中研究最多的是合成肠色素细胞的血清素（5-HT）。肠染色质细胞（EC）储存了脊椎动物体内约95%的血清素。EC细胞的机械和营养刺激导致基底5-HT分泌到粘膜下层。5-羟色胺与位于内禀初级传入神经元（IPANs）上的许多5-羟色胺受体结合。IPANs与中间神经元和运动神经元突触产生蠕动和分泌运动反应。另一方面，初级传入外源性神经元与中枢神经系统交流，产生内脏感觉。5-羟色胺在生理pH值下带电，必须通过5-羟色胺转运体（SERT）通过细胞膜运输去除。肠道5 -羟色胺信号系统成分的改变与消化道疾病有关，包括肠易激综合征（IBS）、炎症性肠病（IBD）和乳糜泻。肠易激综合征是一种常见的疾病，其表现为肠道内运动、分泌和内脏感觉的改变，没有特定的生物学标志物。我们将研究血清素信号系统的作用，以确定它在斑马鱼消化系统中的功能。特异性目的1将进一步确定肠内分泌细胞是如何在肠上皮内被指定的，重点是肠嗜铬细胞以及血清素信号成分的修饰。特异性目标2将在5-羟色胺信号成分改变后，将运动性变化与胚胎斑马鱼肠道内5-羟色胺的实时体内测量联系起来。

DESCRIPTION (provided by applicant): The enteric nervous system plays a critical role in normal function of the intestine. Enteric neurons provide motor and sensory information to generate propulsive movement and maintain organ homeostasis. Homeostasis in the digestive system is also maintained in part by chemical sensors present on different subtypes of enteroendocrine cells. These cells are positioned throughout the intestinal epithelium in order to aid in communicating luminal conditions to enteric neurons within the submucosa. Enteroendocrine cells secrete a variety of mediators to stimulate afferent neurons. One of the most studied of these cells are serotonin (5-HT) synthesizing enterochromaffin cells. Enterochromaffin cells (EC) store about 95% of the serotonin within vertebrates. Mechanical and nutrient stimulation of EC cells results in basal 5-HT secretion into the submucosa. 5-HT binds to numerous 5-HT receptors located on intrinsic primary afferent neurons (IPANs). IPANs synapse with interneurons and motor neurons creating peristaltic and secremotor responses. Primary afferent extrinsic neurons on the other hand communicate with the CNS to create visceral sensation. 5-HT is charged at physiological pH and must be removed by transport across cellular membranes using the serotonin transporter (SERT). Alteration of components of the intestinal serotonin signaling system is associated with digestive diseases including Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease (IBD), and celiac disease. IBS is a common disorder with altered motility, secretion, and visceral sensation within the intestine for which there is no specific biological markers. We will investigate the role of the serotonin signaling system to determine how it functions within the zebrafish digestive system. Specific aim 1 will further identify how enteroendocrine cells are specified within the intestinal epithelium with an emphasis on enterochromaffin cells as well as modification of serotonin signaling components. Specific aim 2 will correlate changes in motility and with real time in vivo measurements of 5-HT within the embryonic zebrafish intestine after alteration of 5-HT signaling components. PUBLIC HEALTH RELEVANCE: This research will contribute to identification of mechanisms by which motility of the digestive tract is acquired. When neurotransmitters critical to motility are disrupted, diseases such as Irritable Bowel Syndrome, Inflammatory Bowel Disease, and celiac disease develop. Genetic defects identified in this research will contribute to understanding these conditions.