Embaby Eman M, Megahed Aya, Mostafa Sally Abdallah, Samy Alaa, Yousef Eman H, Dawood Amal F, Eldesoqui Mamdouh
Department of Physiology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt.
Department of Clinical Pathology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt.
J Exp Zool A Ecol Integr Physiol. 2025 Jun;343(5):590-607. doi: 10.1002/jez.2913. Epub 2025 Mar 10.
Testicular ischemia/reperfusion injury (TI/RI) is a significant clinical contributor to subfertility and infertility resulting from testicular torsion and subsequent detortion. Insufficient nitric oxide (NO) synthesis in TI/RI can result in endothelial dysfunction, as the vascular endothelium fails to produce sufficient NO to sustain appropriate vasodilation and blood perfusion. Many studies have found that NO plays an important role in the I/RI and its increase or decrease can affect the progression and outcome of I/RI. However, the role of NO in I/RI is controversial and complicated. NO derived by endothelial NO synthase (eNOS) shows a protective role in I/RI, while excessive NO derived by inducible NO synthase (iNOS) accelerates inflammation and increases oxidative stress, further aggravating I/RI. Nevertheless, the overexpression of eNOS may exacerbate I/RI. Here we try to investigate the new progress in the understanding of the roles of NO during I/RI. This study examined the interplay between cytotoxic and cytoprotective mechanisms underpinning NO produced from L-citrulline (L-Cit) on TI/R injured rats. Thirty-two adult Sprague-Dawley albino rats were equally randomized into the following groups: normal control group, sham group, TI/R group (3 h/4 h), and TI/R + L-Cit group (600 mg/kg) orally at 1 h before reperfusion. Compared to the TI/R-operated group, the injection of L-Cit markedly enhanced serum concentrations of reproductive hormones (p < 0.05). Elevated SOD, CAT, and GPx activity, along with reduced MDA and NO concentrations, indicated a diminished oxidative stress. The testicular levels of TNF-α, IL-1β, caspase-3, BAX, eNOS, iNOS, and NF-κB p65 were markedly reduced. Histopathological analysis corroborated the protective effect of L-Cit. The findings confirmed molecular models, demonstrating that L-Cit inhibited eNOS, iNOS, and IKKβ. The results showed that giving torsioned rats NO made from L-Cit protected them against hormonal imbalance, oxidative stress, inflammation, and apoptosis in I/RI. This makes L-Cit even more important for protecting against tissue I/RI during surgery. L-Cit not only promoted NO synthesis through eNOS activation, but it also facilitated the neutralization of iNOS production and its pathogenic NO levels during the reperfusion phase in I/R-injured rats.
睾丸缺血/再灌注损伤（TI/RI）是导致睾丸扭转及随后的扭转复位引起的亚生育力和不育症的一个重要临床因素。TI/RI中一氧化氮（NO）合成不足可导致内皮功能障碍，因为血管内皮无法产生足够的NO来维持适当的血管舒张和血液灌注。许多研究发现，NO在缺血/再灌注损伤（I/RI）中起重要作用，其增加或减少会影响I/RI的进展和结果。然而，NO在I/RI中的作用存在争议且复杂。由内皮型一氧化氮合酶（eNOS）产生的NO在I/RI中显示出保护作用，而由诱导型一氧化氮合酶（iNOS）产生的过量NO会加速炎症并增加氧化应激，进一步加重I/RI。然而，eNOS的过度表达可能会加剧I/RI。在此，我们试图探讨对NO在I/RI过程中作用理解的新进展。本研究检测了L-瓜氨酸（L-Cit）产生的NO在TI/R损伤大鼠中细胞毒性和细胞保护机制之间的相互作用。32只成年Sprague-Dawley白化大鼠被平均随机分为以下几组：正常对照组、假手术组、TI/R组（3小时/4小时）以及在再灌注前1小时口服L-Cit组（600mg/kg）。与TI/R手术组相比，注射L-Cit显著提高了生殖激素的血清浓度（p<0.05）。超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GPx）活性升高，同时丙二醛（MDA）和NO浓度降低，表明氧化应激减轻。睾丸中肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）、半胱天冬酶-3（caspase-3）、Bax、eNOS、iNOS和核因子-κB p65的水平显著降低。组织病理学分析证实了L-Cit的保护作用。研究结果证实了分子模型，表明L-Cit抑制eNOS、iNOS和IKKβ。结果表明，给扭转的大鼠补充由L-Cit产生的NO可保护它们免受I/RI中的激素失衡、氧化应激、炎症和细胞凋亡的影响。这使得L-Cit在手术期间预防组织I/RI方面更加重要。L-Cit不仅通过激活eNOS促进NO合成，还在I/R损伤大鼠的再灌注阶段促进iNOS产生及其致病性NO水平的中和。
