Blanco Santos, Hernández Raquel, Franchelli Gustavo, Ramos-Álvarez Manuel Miguel, Peinado María Ángeles
Area of Cell Biology, Department of Experimental Biology, University of Jaén, Campus Las Lagunillas s/n, 23071, Jaén, Spain.
Area of Methodology of the Behavioural Sciences, Department of Psychology, University of Jaén, Campus Las Lagunillas s/n, 23071, Jaén, Spain.
Nitric Oxide. 2017 Jan 30;62:32-43. doi: 10.1016/j.niox.2016.12.001. Epub 2016 Dec 8.
In this work, using a rat model combining ischemia and hypobaric hypoxia (IH), we evaluate the relationships between the antioxidant melatonin and the cerebral nitric oxide/nitric oxide synthase (NO/NOS) system seeking to ascertain whether melatonin exerts its antioxidant protective action by balancing this key pathway, which is highly involved in the cerebral oxidative and nitrosative damage underlying these pathologies. The application of the IH model increases the expression of the three nitric oxide synthase (NOS) isoforms, as well as nitrogen oxide (NOx) levels and nitrotyrosine (n-Tyr) impacts on the cerebral cortex. However, melatonin administration before IH makes nNOS expression response earlier and stronger, but diminishes iNOS and n-Tyr expression, while both eNOS and NOx remain unchanged. These results were corroborated by nicotine adenine dinucleotide phosphate diaphorase (NADPH-d) staining, as indicative of in situ NOS activity. In addition, the rats previously treated with melatonin exhibited a reduction in the oxidative impact evaluated by thiobarbituric acid reactive substances (TBARS). Finally, IH also intensified glial fibrillary acidic protein (GFAP) expression, reduced hypoxia-inducible factor-1alpha (HIF-1α), but did not change nuclear factor kappa B (NF-κB); meanwhile, melatonin did not significantly affect any of these patterns after the application of the IH model. The antioxidant melatonin acts on the NO/NOS system after IH injury balancing the release of NO, reducing peroxynitrite formation and protecting from nitrosative/oxidative damage. In addition, this paper raises questions concerning the classical role of some controversial molecules such as NO, which are of great consequence in the final fate of hypoxic neurons. We conclude that melatonin protects the brain from hypoxic/ischemic-derived damage in the first steps of the ischemic cascade, influencing the NO/NOS pathway and reducing oxidative and nitrosative stress.
在本研究中，我们使用缺血合并低压缺氧（IH）大鼠模型，评估抗氧化剂褪黑素与脑一氧化氮/一氧化氮合酶（NO/NOS）系统之间的关系，旨在确定褪黑素是否通过平衡这一关键途径发挥其抗氧化保护作用，该途径与这些病理状态下的脑氧化和亚硝化损伤密切相关。IH模型的应用增加了三种一氧化氮合酶（NOS）同工型的表达，以及一氧化氮（NOx）水平和硝基酪氨酸（n-Tyr）对大脑皮层的影响。然而，在IH之前给予褪黑素使nNOS表达反应更早、更强，但减少了iNOS和n-Tyr表达，而eNOS和NOx保持不变。烟酰胺腺嘌呤二核苷酸磷酸黄递酶（NADPH-d）染色证实了这些结果，表明原位NOS活性。此外，先前用褪黑素处理的大鼠通过硫代巴比妥酸反应性物质（TBARS）评估的氧化影响有所降低。最后，IH还增强了胶质纤维酸性蛋白（GFAP）的表达，降低了缺氧诱导因子-1α（HIF-1α），但未改变核因子κB（NF-κB）；同时，在应用IH模型后，褪黑素对这些模式均无显著影响。抗氧化剂褪黑素在IH损伤后作用于NO/NOS系统，平衡NO的释放，减少过氧亚硝酸盐的形成，并防止亚硝化/氧化损伤。此外，本文还提出了一些关于某些有争议分子如NO的经典作用的问题，这些问题对缺氧神经元的最终命运具有重要影响。我们得出结论，褪黑素在缺血级联反应的第一步保护大脑免受缺氧/缺血性损伤，影响NO/NOS途径并降低氧化和亚硝化应激。
