内皮素A受体/C类纤维在慢性精神应激后间质性膀胱炎疼痛中的作用研究

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic condition characterized by pelvic pain and voiding symptoms. To date, the etiology remains poorly understood and none of therapeutic applications is curative. Clinical studies have revealed the key role of chronic psychological stress in exacerbation and development of IC/BPS. By conducting a water avoidance stress-induced IC/BPS rat model, we have found that bladder pain after stress may be related to sensitized bladder C fiber. Additionally, previous study also indicated an upregulated mRNA expression of endothelin-1 and its type A receptor (ETAR). ETAR has been proved to enhance nerve sensitization and painful feeling. Therefore, we hypothesize that chronic psychological stress induces C fiber sensitization via upregulating the expression of ETAR, which finally triggers bladder pain. To this end, the project will apply water avoidance stress model to analyze the expression level of ETAR, identify the location of ETAR in the bladder tissue and dorsal root ganglion neurons innervating the bladder, and demonstrate whether ETAR activation functionally trigger bladder pain through bladder C fiber. Successful completion of the project will determine the relationship between chronic stress and IC/BPS, as well as the mechanism for bladder pain in IC/BPS, providing new theoretical basis for the prevention and treatment of IC/BPS.

间质性膀胱炎/膀胱疼痛综合征（IC/BPS）以膀胱疼痛为特点，发病机制尚不清，治疗效果欠佳。研究显示慢性精神应激与IC/BPS疼痛密切相关。申请者在前期研究中构建了慢性精神应激（避水应激）相关性IC/BPS大鼠模型,并发现应激后膀胱疼痛可能与降钙素基因相关肽(CGRP)免疫阳性的C类感觉神经纤维敏感性增高有关，与此同时脊髓背根神经节中内皮素-1的A型受体（ETAR）mRNA表达上调。ETAR与神经兴奋及多种疼痛有关，因此我们推测，慢性精神应激通过上调ETAR诱导膀胱C类纤维敏感化进而导致膀胱疼痛。为此，本课题采用慢性避水应激模型：在组织学水平，分析ETAR及CGRP在膀胱和脊髓背根神经节内定位、表达及分布的变化情况；在功能学水平，明确ETAR激活是否诱导膀胱疼痛，以及证实该作用是否与C类纤维有关。研究结果有助于阐明IC/BPS的发病机制，为临床治疗提供理论依据和实验基础。

间质性膀胱炎/膀胱疼痛综合征（IC/BPS）以膀胱疼痛为特点，发病机制尚不清，治疗效果欠佳。研究显示慢性精神应激与IC/BPS疼痛密切相关。申请者在前期研究中构建了慢性精神应激（避水应激）相关性IC/BPS大鼠模型,并发现应激后膀胱疼痛可能与降钙素基因相关肽(CGRP)免疫阳性的C类感觉神经纤维敏感性增高有关，但具体机制仍不明确。本研究以膀胱疼痛为重点，采用慢性避水应激（WAS）构建IC/BPS大鼠模型，开展相关动物实验，探讨内皮素-1（ET-1）及其信号通路诱导慢性精神应激后膀胱疼痛中的作用。本研究发现：1.免疫荧光显示内皮素A型受体（ETAR）在膀胱组织及L6 DRG中与CGRP共表达。2.WB及qRT-PCR结果显示WAS在一定程度上提高ETAR在膀胱和DRG中的表达，辣椒素预处理可降低ETAR表达量。3.甲苯胺蓝染色显示WAS可显著提高膀胱组织中总肥大细胞数，而辣椒素可减轻肥大细胞浸润。4.尿流动力学结果显示WAS可显著增强膀胱感觉尤其是痛觉敏感性，而辣椒辣素阻断膀胱C类纤维后可明显减轻该作用。5.膀胱灌注ET-1可协同WAS进一步增强大鼠膀胱感觉尤其是痛觉传入，辣椒素可阻断ET-1的痛觉诱导作用。因此，慢性精神应激可诱导膀胱疼痛，而这可能与慢性精神应激后C类神经纤维上内皮素受体激活有关。总之，本研究进一步阐述了慢性精神应激、膀胱疼痛、ET-1及其受体三者间的紧密关系，以期为治疗IC/BPS提供有效的靶点。