Nitric Oxide/cGMP Modulation of Corporal Fibrosis Caused by Neuropraxia

描述（申请人提供）：勃起功能障碍（ED）是前列腺癌根治性前列腺切除术（RP）后常见的并发症，是由于海绵体神经在手术中受到损伤。尽管神经保留技术有所进步，但仍有许多男性在手术后出现ED。在这些手术技术完善到可以在不对神经造成任何暂时或永久性损伤的情况下进行手术之前，将重点放在预防由于神经损伤而导致的身体组织的有害和不可逆转的变化上似乎是合乎逻辑的。我们假设这一过程可以在双侧海绵体神经切除（BCNR）的大鼠身上进行研究，BCNR是可能发生在神经上的最严重的损伤形式，或者双侧神经挤压模型（BCNC）是一种不太严重的神经损伤形式，因为没有轴突的横断，并且在转基因小鼠身上进行研究，以研究这些假设：(1) BCNR/BCNC诱导的下体纤维化和平滑肌细胞（SMC）凋亡可通过持续和长期给药PDE5抑制剂中的任何一种，通过增加体内NO和cGMP，从药理学上预防。由于神经损伤引起的氧化应激和tgf - β水平的降低，这种治疗导致胶原沉积减少（纤维化减少）和SM转换阳性（SMC数量增加）。(2) BCNR/BCNC诱导的神经损伤可能通过调节NO/cGMP通路而得到改善；通过激活Pi3K-Akt通路，诱导神经发生，导致部分轴突再生，改善勃起反应。

DESCRIPTION (provided by applicant): Erectile dysfunction (ED) is a common complication after radical prostatectomy (RP) for prostate cancer and is due to the injury of the cavernosal nerve during surgery. Despite the improvement of the nerve sparing technique, still many men develop ED after surgery. Until these surgical techniques are perfected to the point where this can be performed without any temporary or permanent injury to the nerves, it seems logical to focus on the prevention of the detrimental and irreversible changes that befall the corporal tissue as a result of the neural injury. We postulate that this process can be studied in rats subjected to bilateral cavernosal nerve resection (BCNR) which is the most severe form of injury that can occur to the nerves, or the bilateral nerve crush model (BCNC) which is a less severe form of neural injury since there is no transection of the axon, and in transgenic mice, to investigate these hypotheses: (1) the corporal fibrosis and smooth muscle cell (SMC) apoptosis induced by BCNR/BCNC can be prevented pharmacologically by the continuous and long-term administration of either PDE5 inhibitors, which increases intracorporeal NO and cGMP. Such treatment leads to a reduction in collagen deposition (decrease in fibrosis) and a positive SM turnover (increase in SMC number) as a result of a reduction in the increased oxidative stress and TGF-beta levels induced by the neural injury. (2) The neural injury induced by BCNR/BCNC may be ameliorated by the modulation of NO/cGMP pathway; through the activation of Pi3K-Akt pathway, inducing neurogenesis, leading to partial axonal regeneration and improvement of the erectile response. To test these hypotheses we propose: Aim 1: To determine the relative effects of modulating the NO and cGMP pathway on corporal collagen and SM turnover rates oxidative stress, neuronal, and smooth muscle apoptosis after BCNR. Aim 2: To determine the mechanism by which NO and/or cGMP preserves the corporal SMC and to ascertain the roles of PKG (protein kinase G) or PKA (protein kinase A) in this process. Aim 3: To determine whether the stimulation of the NO/cGMP pathway induces the release of neurotrophic factors that may lead to regeneration of cavernosal nerves via the Pi3K-AKT pathway. Endpoints: (a) functional determinations of erectile response like electrical field stimulation and cavernosometry; (b) immunohistochemistry for markers of fibrosis, oxidative stress, nitrosative reaction, collagen, SMC turnover, nerve regeneration, and neurotrophic factors; (c) Western blot analysis for some of these markers; (d) assays with selective NO/cGMP modulators in cell culture.