Na Channels in Afferents after Bladder Obstruction

膀胱梗阻后传入神经中的 Na 通道

• 批准号: 6775531
• 负责人: WILLIAM DONALD STEERS
• 金额: $ 25.93万
• 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/6775531
• 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）：良性前列腺增生（BPH）在四分之一的男性中发展。超过10亿美元用于缓解由于膀胱过度活动症（OAB）引起的BPH的烦恼症状。这些症状可能包括尿急、尿频、尿失禁和急迫性尿失禁。症状可以通过局部麻醉和微创手术缓解，这些手术使来自膀胱和尿道的感觉输入变钝，但无法解除阻塞。使用啮齿类动物的部分尿道结扎模型，研究人员假设OAB可能起源于下尿路肌肉和神经的变化。梗阻（OBS）大鼠表现出排尿频率和逼尿肌过度活动时间相关的传入肥大，脊髓反射增强，神经生长因子（NGF）的上升的发展。对NGF的免疫阻止神经可塑性和OAB。因此，认为作为细胞因子的NGF参与这些事件，认为NGF影响传入兴奋性的能力部分源自改变Na电导，这反过来又取决于Na通道同种型表达。数据表明，从OBS大鼠的传入表现出减少免疫组织化学（IHC）染色的Nay1.8亚型。该Na α亚基在C纤维传入中引起河豚毒素抗性（TTX-R）钠（Na）电流。此外，针对该同种型的反义（AS）而非错配寡脱氧核苷酸（ODN）降低OAB。我们推测在OBS大鼠中1）存在增加的传入兴奋性，2）OAB和传入兴奋性是由于钠（Na）电导的改变，3）使用鞘内AS ODN敲低Na通道亚型降低传入过度兴奋性和OAB，和4）NGF参与增强的传入兴奋性、Na通道功能和/或亚型表达的改变的发生。将通过确定与假手术相比，梗阻是否1）基于膜片钳分析改变标记的传入膀胱神经元的电特性，2）使用IHC和Western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随着排尿行为的去结扎和正常化而可逆，来检验这些假设。通过观察NGF免疫或trkA拮抗剂是否阻止了与对照组相比的OBS电特性和蛋白表达的变化，阐明了NGF协调这些事件的能力。对这些细胞过程的洞察可以被利用来开发基于传入的OAB治疗，采用基于药理学、分子或基因的策略。