Serotonin signaling in control of the Lower Urinary Tract

项目总结 下尿路(LUT)的正常功能需要神经元活动的协调才能允许膀胱 充填以储存尿液，随后进行膀胱收缩，在适当的时间完成尿液排出 时间和地点。调节膀胱控制的神经元件的发育缺陷可能 导致患者出现神经性膀胱、大小便失禁、尿潴留或膀胱疼痛等问题。 这些LUT疾病导致患者的生活质量下降，增加了医疗成本，并给患者带来负担 医疗保健系统。虽然我们知道外周神经系统的骶骨成分， 参与这些膀胱突起的调节，包括背根节(DRG)感觉神经元 和自主(运动)盆腔神经元，我们对这些神经元是如何 以及发育过程中的缺陷如何导致先天性膀胱控制缺陷。通过测量 5-羟色胺在小鼠盆神经节发育过程中的基因表达 在发育中的DRG的感觉神经元中也有表达的受体。功能丧失的小鼠 这些5-羟色胺受体的突变，特别是5-羟色胺3型受体(5-HT3)，具有异常 膀胱壁神经的发育，后来表现为尿液滞留。我们的前期工作是 分离培养的骶骨神经脊干细胞表明5-HT3信号的干扰 神经元分化。我们推测，在5-HT3突变小鼠中观察到的膀胱缺陷发生了 这不仅是由于缺乏5-HT3信号的发育中的神经末梢过度分枝的结果，而且 由于改变了细胞命运规范导致了发展中的DRG类型之间的不平衡 和盆神经节神经元。细胞命运指定是一种新的功能，以前没有被归因于 到5-HT3，并对在发育过程中形成的神经元的类型有显著影响 膀胱神经支配。这种神经元分化的改变易导致膀胱功能缺陷。 控制并增加对膀胱痛易感性的可能性。提出了三个目标： 将详细阐述5-HT3信号在DRG和盆神经节神经元发育过程中的作用 支配膀胱。在目标1中，我们将使用遗传学和药理学方法来确定何时5- HT3信号是形成和维持正常的膀胱神经支配所必需的。在《目标2》中，我们将使用 Cre：Htr3a功能突变获得和丢失的loxP谱系追踪研究 受5-HT3信号影响的过程和时间段。在目标3中，我们将确定 发育过程中5-HT3信号的中断增加了对膀胱炎性疼痛的易感性。 这些研究将产生神经发育缺陷导致膀胱的机械性知识。 并将帮助泌尿科医生为患者设计个性化的治疗方案。

PROJECT SUMMARY Normal function of the lower urinary tract (LUT) requires coordination of neuronal activity to allow bladder filling for urine storage followed later by bladder contraction to accomplish urine expulsion at an appropriate time and place. Deficiencies in the development of the neural elements that mediate bladder control can lead to problems in patients such as neurogenic bladder, incontinence, urinary retention, or bladder pain. These LUT diseases result in reduced quality of life for patients, increase healthcare costs, and burden the health care system. While we know that the sacral elements of the peripheral nervous system, which participate in regulation of these bladder processes, include dorsal root ganglion (DRG) sensory neurons and autonomic (motor) pelvic neurons, there are many gaps in our knowledge regarding how these neurons develop and how deficits during development lead to congenital defects in bladder control. By surveying gene expression during development of pelvic ganglia in mice we have identified up-regulation of serotonin receptors that are also expressed in sensory neurons of developing DRG. Mice with loss of function mutations in these serotonin receptors, specifically the serotonin type 3 receptor (5-HT3), have abnormal development of nerves in the bladder wall and later exhibit urinary retention. Our preliminary work in isolated cultures of sacral neural crest stem cells indicates that perturbations of 5-HT3 signaling disrupt neuronal differentiation. We postulate that the bladder deficiencies observed in 5-HT3 mutant mice occur not only as the result of hyper-arborization of developing nerve terminals that lack 5-HT3 signaling, but also as a consequence of altered cell fate specification leading to imbalances among types of developing DRG and pelvic ganglia neurons. Cell fate specification is a novel function that has not previously been ascribed to 5-HT3 and has potential for pronounced impact on the types of neurons formed during development of bladder innervation. Such alterations in neuronal differentiation would predispose to deficiencies in bladder control and add to the potential for increased susceptibility to bladder pain. Three aims are proposed that will elaborate roles for 5-HT3 signaling during development of DRG and pelvic ganglia neurons that innervate the bladder. In Aim 1 we will use genetic and pharmacologic approaches to determine when 5- HT3 signaling is required to develop and maintain normal bladder innervation. In Aim 2 we will use Cre:LoxP lineage tracing studies in Htr3a gain and loss of function mutants to define the developmental processes and time periods that are affected by 5-HT3 signaling. In Aim 3 we will determine whether disruptions of 5-HT3 signaling during development increase vulnerabilty to bladder inflammatory pain. These studies will generate mechanistic knowledge of deficits in neural development that lead to bladder disease and will aid urologists in sculpting personalized therapies for patients.