Serotonin signaling in control of the Lower Urinary Tract

项目摘要 下尿路（LUT）的正常功能需要神经元活动的协调， 充尿，然后膀胱收缩，以适当的速度排出尿液。 时间和地点。介导膀胱控制的神经元件发育缺陷， 导致患者出现问题，例如神经性膀胱、失禁、尿潴留或膀胱疼痛。 这些LUT疾病导致患者的生活质量降低，增加医疗保健成本，并加重患者的负担。 医疗保健系统。虽然我们知道周围神经系统的骶骨成分， 参与这些膀胱过程的调节，包括背根神经节（DRG）感觉神经元 和自主（运动）骨盆神经元，我们的知识中有很多空白，关于这些神经元如何 以及发育过程中的缺陷如何导致膀胱控制的先天性缺陷。通过调查 在小鼠盆神经节发育过程中的基因表达，我们已经确定了5-羟色胺的上调 这些受体也在发育中的DRG的感觉神经元中表达。功能丧失小鼠 这些5-羟色胺受体的突变，特别是5-羟色胺3型受体（5-HT 3），具有异常的 膀胱壁神经发育，随后出现尿潴留。我们的初步工作， 分离培养的骶神经嵴干细胞表明，5-HT 3信号的扰动破坏了 神经元分化我们假设在5-HT 3突变小鼠中观察到的膀胱缺陷发生在 这不仅是由于缺乏5-HT 3信号传导的发育中的神经末梢过度树枝化， 由于细胞命运的改变导致DRG发育类型之间的不平衡， 和骨盆神经节神经元。细胞命运特化是一个新的功能，以前没有被归因于 5-HT 3，并有可能对发育过程中形成的神经元类型产生显著影响。 膀胱神经支配神经元分化的这种改变将使膀胱功能缺陷 控制并增加膀胱疼痛易感性的可能性。提出了三个目标， 将详细阐述5-HT 3信号传导在DRG和盆神经节神经元发育过程中的作用， 刺激膀胱在目标1中，我们将使用遗传学和药理学方法来确定何时5- HT 3信号传导是发展和维持正常膀胱神经支配所必需的。在目标2中，我们将使用 在Htr 3a功能获得和丧失突变体中进行Cre：LoxP谱系追踪研究，以确定发育 过程和时间周期受5-HT 3信号。在目标3中，我们将确定 发育期间5-HT 3信号传导的中断增加了膀胱炎性疼痛的易感性。 这些研究将产生神经发育缺陷的机制知识，导致膀胱 这将有助于泌尿科医生为患者制定个性化治疗方案。

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.