Cystitis-Induced Plasticity of Micturitin Reflexes

描述（由申请人提供）：膀胱疼痛综合征(BPS)/间质性膀胱炎（IC）是一种慢性疼痛综合征，其特征是至少一种泌尿系统症状与膀胱相关的疼痛、压力或不适。BPS/IC对生活质量和经济负担的影响巨大。在本研究期间，我们假设与BPS/IC相关的疼痛涉及内脏感觉/膀胱感觉生理的改变。内脏感觉的改变可能部分由膀胱炎症变化介导，包括神经生长因子（NGF）。在BPS/IC患者中特异性抑制NGF的单克隆抗体治疗证明了概念的证明；然而，由于严重的副作用，临床试验已经停止了招募。显然，需要在NGF之外设立更多的目标。通过这一竞争性更新的应用，我们提出了目标，将提供额外的NGF介导的多效性变化的机制，这些变化有助于慢性NGF过表达（NGF- oe）的新型转基因小鼠模型的膀胱高反射和盆腔超敏反应，该模型使用了在上一个资助周期中表征的尿路特异性uroplakin II启动子。目前的假设是，伴随BPS/IC的尿频增加和感觉改变是由于膀胱反射感觉肢体中神经化学介质和感觉换能器瞬时受体电位（TRPV）家族成员TRPV4的表达、功能和相互作用的改变。这些研究考察了神经肽、PACAP、受体PAC1和TRPV4对NGF-OE小鼠排尿频率和体细胞敏感性增加的贡献和相互作用。目的1：我们假设NGF- oe小鼠模型尿路上皮和腰骶背根神经节（DRG）中NGF的过表达可诱导DRG膀胱传入细胞和膀胱尿路上皮细胞中感觉传感器TRPV4的上调。我们假设TRPV4在排尿反射的感觉成分（尿路上皮，DRG）中的组织特异性表达有助于NGF-OE小鼠的膀胱高反射和盆腔超敏反应。目的2：我们假设TRPV4和PACAP/PAC1之间的相互作用可能代表了一种新的机制，通过该机制，PACAP/PAC1信号激活磷脂酶C和三磷酸肌醇，使TRPV4介导的排尿行为和疼痛感觉的变化变得敏感。此外，我们假设PAC1和TRPV4在膀胱传入DRG和尿路上皮细胞中共表达。我们将采用多学科方法，包括解剖学、生物化学、分子、电生理和功能方法，以及一种新的离体外周神经记录方法来解决这些问题。研究结果将为改善膀胱功能和内脏感觉提供具有治疗潜力的新靶点。

DESCRIPTION (provided by applicant): Bladder pain syndrome (BPS)/interstitial cystitis (IC) is a chronic pain syndrome characterized by pain, pressure or discomfort perceived to be bladder related with at least one urinary symptom. The impact of BPS/IC on quality of life and economic burden are enormous. Over the life of this grant, we have hypothesized that pain associated with BPS/IC involves an alteration of visceral sensation/bladder sensory physiology. Changes in visceral sensation may be mediated, in part, by inflammatory changes in the urinary bladder including nerve growth factor (NGF). Monoclonal antibody treatment that specifically inhibits NGF in patients with BPS/IC demonstrates proof of concept; however, clinical trials have halted enrollment due to severe side effects. The need for additional targets beyond NGF is clear. With this competitive renewal application, we propose aims that will provide mechanistic insight into additional NGF-mediated pleiotropic changes that contribute to urinary bladder hyperreflexia and pelvic hypersensitivity in a novel transgenic mouse model of chronic NGF overexpression (NGF-OE) using the urothelium-specific uroplakin II promoter that was characterized during the last funding cycle. The working hypothesis is that increases in urinary frequency and altered sensation that accompany BPS/IC are due to an alteration in the expression, function and interactions of neurochemical mediators and the sensory transducer, transient receptor potential (TRPV) family member TRPV4, in the sensory limb of the urinary bladder reflex. These studies examine the contributions of and interactions between the neuropeptide, PACAP, and receptor PAC1 and TRPV4 to increased voiding frequency and somatic sensitivity in NGF-OE mice. Aim 1: We hypothesize that NGF overexpression exhibited in urothelium and lumbosacral dorsal root ganglia (DRG) of the NGF-OE mouse model induces upregulation of the sensory transducer, TRPV4, in bladder afferent cells in DRG and in urothelial cells of the urinary bladder. We hypothesize that tissue-specific expression of TRPV4, in sensory components (urothelium, DRG) of the micturition reflex contributes to urinary bladder hyperreflexia and pelvic hypersensitivity in NGF-OE mice. Aim 2: We hypothesize that interactions between TRPV4 and PACAP/PAC1 may represent a novel mechanism by which PACAP/PAC1 signaling activates phospholipase C and inositol triphosphate to sensitize TRPV4-mediated changes in voiding behavior and painful sensation. Furthermore, we hypothesize that PAC1 and TRPV4 are co-expressed in bladder afferent DRG and urothelial cells. We will use a multidisciplinary approach including anatomical, biochemical, molecular, electrophysiological, and functional methodologies and a novel ex vivo peripheral nerve recording approach to address these aims. Results will provide key insights into new targets with therapeutic potential to improve urinary bladder function and visceral sensation.