Cystitis-Induced Plasticity of Micturition Reflexes

描述（由申请人提供）：膀胱疼痛综合征(PBS)/间质性膀胱炎（IC）是一种慢性症状，以尿频、尿急、耻骨上、盆腔疼痛和膀胱镜检查结果为特征。本研究建议的假设是，伴随PBS/IC的排尿频率增加和感觉改变是由于排尿反射的主要传入肢的改变，部分是由于脊髓神经元间机制的改变。膀胱炎患者尿频增加也可能是由于排尿反射的传出肢发生改变。这些变化的结合通过改变神经元间水平和骨盆神经节的突触传递，促进了脊髓反射通路到膀胱。神经生长因子（NGF）和NGF/受体酪氨酸激酶（TrkA）相互作用对炎症诱导的膀胱功能改变、下尿路（LUT）通路的神经化学可塑性和LUT反射的中枢组织的贡献已经被定义。本研究的目的是利用CYP大鼠膀胱炎症模型、一种新型的慢性过表达NGF小鼠系（UPII-NGFv2）和多学科实验方法，提供炎症诱导的排尿反射神经控制变化的机制。目的1：为了模拟慢性膀胱炎症和PBS/IC的环境，将使用尿路上皮中慢性过表达NGF （UPII-NGFv2）的小鼠，利用有意识的膀胱测量、免疫组织化学和细胞内记录技术来确定NGF在调节膀胱反射的功能、神经化学和组织可塑性方面的作用。神经可塑性是否继发于排尿反射的神经化学表型的变化将被确定。目的2:p75NTR和Trk受体相互作用，调节TrkA受体对其同源配体NGF的亲和力。将确定Trk与p75NTR介导的信号在对照组、cypp处理的啮齿动物、UPII-NGFv2和回交野生型小鼠的LUT通路中的作用。这些研究将使用药理学工具来阻断NGF/TrkA与NGF/p75信号传导。目的3：神经营养因子诱导信号的生物学作用尚不清楚，特别是在LUT中。我们将测定大鼠和UPII-NGFv2小鼠在cypp诱导的膀胱炎后腰骶脊髓、DRG和膀胱中ERK1/2、ERK5和Akt的颞活化情况。在给予ERK或PI3K抑制剂后，神经化学性质和脊髓排尿反射的组织将被确定。这些研究可能为未来PBS/IC的潜在靶点和治疗干预提供见解。

DESCRIPTION (provided by applicant): Painful Bladder Syndrome (PBS)/Interstitial Cystitis (IC) is a chronic symptom-complex characterized by urinary frequency, urgency, suprapubic, pelvic pain and cystoscopic findings. The hypothesis for this research proposal is that increases in voiding frequency and altered sensation that accompany PBS/IC are due to an alteration in the primary afferent limb of the micturition reflex and, in part, to an alteration in interneuronal mechanisms in the spinal cord. Increased urinary frequency with cystitis may also be due to an alteration in the efferent limb of the micturition reflex. The combination of these changes facilitates a spinal reflex pathway to the urinary bladder by altering synaptic transmission at the interneuronal level and to the pelvic ganglia. The contribution of nerve growth factor (NGF) and NGF/receptor tyrosine kinase (TrkA) interactions to inflammatory-induced changes in urinary bladder function, neurochemical plasticity in lower urinary tract (LUT) pathways and central organization of LUT reflexes has been defined. The proposed aims provide mechanistic insight into inflammation-induced changes in neural control of micturition reflexes using the CYP rat model of urinary bladder inflammation, a novel, chronic overexpressing NGF mouse line (UPII-NGFv2) and a multidisciplinary experimental approach. Aim 1: To mimic the environment of chronic bladder inflammation and PBS/IC, mice with chronic overexpression of NGF in the urothelium (UPII-NGFv2) will be used to determine the role that NGF plays in mediating functional, neurochemical and organizational plasticity of bladder reflexes using conscious cystometry, immunohistochemistry and intracellular recording techniques. Whether neural plasticity is secondary to changes in neurochemical phenotype of the micturition reflex will be determined. Aim 2: p75NTR and Trk receptors interact to regulate the affinity of TrkA receptor for its cognate ligand, NGF. The involvement of Trk versus p75NTR mediated signaling in LUT pathways in control, CYP-treated rodents, UPII-NGFv2 and backcrossed wildtype mice will be determined. These studies will use pharmacological tools to block NGF/TrkA versus NGF/p75 signaling. Aim 3: The biological roles of neurotrophin-induced signals are unknown especially in the LUT. The temporal activation of ERK1/2, ERK5 and Akt in lumbosacral spinal cord, DRG and urinary bladder after CYP-induced cystitis in rats and in UPII-NGFv2 mice will be determined. The neurochemical properties and the organization of spinal micturition reflexes after administration of ERK or PI3K inhibitors will be determined. These studies may provide insights into potential targets and therapeutic interventions for PBS/IC in the future. PUBLIC HEALTH RELEVANCE Painful Bladder Syndrome (PBS)/Interstitial Cystitis (IC) is a chronic symptom-complex characterized by urinary frequency, urgency, suprapubic, pelvic pain and cystoscopic findings. Inflammation-induced expression of growth factors (e.g. nerve growth factor, NGF) in the urinary bladder or urine of women with PBS/IC and subsequent interactions with the central and peripheral nervous system may contribute to these symptoms. These studies will determine how NGF interactions with membrane bound receptors and activation of cellular signaling events could contribute to urinary bladder dysfunction and changes in sensory processing. These studies will contribute to the understanding of inflammation-induced changes in chronic bladder inflammation and may provide insights into potential targets and therapeutic interventions for PBS/IC in the future.