Na Channels in Afferents after Bladder Obstruction

膀胱梗阻后传入神经中的 Na 通道

• 批准号: 6681096
• 负责人: WILLIAM DONALD STEERS
• 金额: $ 28.04万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6681096
• 关键词: action potentials; autonomic nervous system; immunocytochemistry; laboratory rat; nerve growth factors; neurons; peripheral nervous system; protein isoforms; sodium channel; tissue /cell culture; urinary bladder disorder; voltage /patch clamp; western blottings

DESCRIPTION (provided by applicant): Benign prostatic hyperplasia (BPH) develops in one out of four men. In excess of $1 billion is spent to relieve bothersome symptoms of BPH due to an overactive bladder (OAB). These symptoms may include urgency, frequency, nocturia and urge incontinence. Symptoms can be relieved by local anesthetics and minimally invasive procedures that blunt sensory input from the bladder and urethra yet fail to un-obstruct. Using the partial urethral ligation model in rodents, investigators postulate that OAB may originate from changes in muscle and nerves in the lower urinary tract. Obstructed (OBS) rats exhibit urinary frequency and detrusor overactivity temporally correlated to the development of afferent hypertrophy, an enhanced spinal reflex, and a rise in nerve growth factor (NGF). Immunity to NGF prevents both neural plasticity and OAB. Therefore, NGF acting as a cytokine is thought to participate in these events, NGF's ability to influence afferent excitability is thought to derive, in part, from altering Na conductances, which in turn depends on Na channel isoform expression. Data suggests that afferents from OBS rats exhibit decreased immunohistochemical (IHC) staining for the Nay1.8 isoform. This Na alpha subunit gives rise to tetrodotoxin resistant (TTX-R) sodium (Na) currents in C-fiber afferents. Moreover, an antisense (AS) but not mismatch oligodeoxynucleotide (ODN) against this isoform reduces OAB. We postulate that in OBS rats 1) increased afferent excitability exists, 2) OAB and afferent excitability are due to an alteration in sodium (Na) conductance, 3) knockdown of Na channel isoform(s) using intrathecal AS ODN reduces afferent hyperexcitability and OAB, and 4) NGF participates in the genesis of enhanced afferent excitability, alterations in Na channel function and/or isoform expression. These hypotheses will be tested by determining whether obstruction compared to sham surgery 1) alters electrical properties of labeled afferent bladder neurons based on patch clamp analysis, 2) changes expression of Na channel isoforms using IHC and Western blotting, and 3) whether alterations in excitability or protein expression are reversible with deligation and normalization of voiding behavior. The ability of NGF to orchestrate these events will be elucidated by noting if NGF immunity or trkA antagonists prevent changes in electrical properties and protein expression in OBS compared to controls. Insight into these cellular processes could be exploited to develop afferent based treatments for OAB employing pharmacologic, molecular or gene based strategies.

描述（由申请人提供）：四分之一的男性患有良性前列腺增生 (BPH)。超过 10 亿美元用于缓解膀胱过度活动症 (OAB) 引起的 BPH 的烦人症状。这些症状可能包括尿急、尿频、夜尿和急迫性尿失禁。局部麻醉剂和微创手术可以缓解膀胱和尿道的感觉输入，但无法解除阻塞。研究人员利用啮齿类动物的部分尿道结扎模型，推测 OAB 可能源于下尿路肌肉和神经的变化。梗阻（OBS）大鼠表现出尿频和逼尿肌过度活动，与传入神经肥大、脊髓反射增强和神经生长因子（NGF）升高的发展暂时相关。对 NGF 的免疫力可防止神经可塑性和 OAB。因此，NGF 作为细胞因子被认为参与了这些事件，NGF 影响传入兴奋性的能力被认为部分源自 Na 电导的改变，而 Na 电导又取决于 Na 通道同种型的表达。数据表明，OBS 大鼠的传入神经中 Nay1.8 亚型的免疫组织化学 (IHC) 染色减少。该 Na α 亚基在 C 纤维传入神经中产生抗河豚毒素 (TTX-R) 钠 (Na) 电流。此外，针对该异构体的反义（AS）而非错配寡脱氧核苷酸（ODN）会减少OAB。我们假设 OBS 大鼠中 1) 存在传入兴奋性增加，2) OAB 和传入兴奋性是由于钠 (Na) 电导的改变所致，3) 使用鞘内 AS ODN 敲低 Na 通道亚型可降低传入过度兴奋性和 OAB，4) NGF 参与传入兴奋性增强、Na 通道功能和/或亚型改变的发生 表达。这些假设将通过确定与假手术相比阻塞是否1）改变基于膜片钳分析的标记传入膀胱神经元的电特性，2）使用IHC和蛋白质印迹改变Na通道亚型的表达，以及3）兴奋性或蛋白质表达的改变是否可通过去结扎和排尿行为正常化来进行测试。 NGF 协调这些事件的能力将通过观察 NGF 免疫或 trkA 拮抗剂是否阻止 OBS 与对照相比电特性和蛋白质表达的变化来阐明。可以利用对这些细胞过程的深入了解，采用药理学、分子或基因策略来开发基于传入的 OAB 治疗方法。