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)后的常见并发症，是由于手术中海绵体神经损伤所致。尽管保留神经的技术有所改进，但仍有许多男性术后出现勃起功能障碍。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，似乎应该把重点放在预防由于神经损伤而发生在躯体组织上的有害和不可逆转的变化上。我们推测，这一过程可以在双侧海绵体神经切除(BCNR)或双侧海绵体神经挤压模型(BCNC)的大鼠中得到研究，BCNR是一种最严重的神经损伤形式，因为没有轴突切断，而双侧神经挤压模型是一种不那么严重的神经损伤形式，因此在转基因小鼠中，为了研究这些假说：(1)PDE5抑制剂的持续和长期给予均可从药理上防止BCNR/BCNC诱导的体部纤维化和平滑肌细胞(SMC)凋亡，PDE5抑制剂可以增加中枢NO和cGMP。这种治疗导致胶原沉积减少(纤维化减少)和正SM周转(SMC数量增加)，这是神经损伤引起的氧化应激和转化生长因子-β水平减少的结果。(2)BCNR/BCnc所致的神经损伤可能通过调节NO/cGMP通路，通过激活PI3K-Akt通路，诱导神经再生，导致部分轴突再生，改善勃起反应。 为了检验这些假设，我们提出： 目的：探讨调控NO和cGMP途径对BCNR后小体胶原和SM周转率、氧化应激、神经细胞和平滑肌细胞凋亡的影响。 目的：探讨一氧化氮(NO)和/或环鸟苷酸(CGMP)对体部SMC的保护机制，以及蛋白激酶G(PKG)和蛋白激酶A(PKA)在此过程中的作用。 目的：探讨刺激NO/cGMP通路是否诱导神经营养因子的释放，从而通过PI3K-AKT通路促进海绵体神经再生。 终点：(A)勃起反应的功能测定，如电场刺激和海绵体测量；(B)纤维化、氧化应激、亚硝化反应、胶原、SMC周转、神经再生和神经营养因子的免疫组织化学标记；(C)其中一些标记的蛋白质印迹分析；(D)细胞培养中选择性NO/cGMP调节剂的分析。

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.