Fatokun Amos A, Stone Trevor W, Smith Robert A
Faculty of Biomedical and Life Sciences, Division of Neuroscience and Biomedical Systems, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
Brain Res. 2008 Sep 16;1230:265-72. doi: 10.1016/j.brainres.2008.06.109. Epub 2008 Jul 8.
Nitric oxide (NO) induces cell proliferation or cell death, depending on the cell type involved, the isoform of nitric oxide synthase activated, and its cellular localisation. In neurons, the damaging effect of NO is usually attributed to the highly toxic peroxynitrite, formed by its reaction with superoxide. Peroxynitrite induces DNA damage and consequently the activation of poly (ADP-ribose) polymerase (PARP). This study set out to examine the contribution of peroxynitrite to the damage induced in cerebellar granule neurons (CGNs) by treatment with the NO donor S-nitroso-N-acetylpenicillamine (SNAP), for short (6 h) or prolonged (24 h) exposures. The Alamar blue assay was used to quantify CGN viability, which was also assessed by morphological examination. SNAP (10 microM-1 mM) induced a concentration- and time-dependent reduction of CGN viability, with associated damage to cell bodies and neurite processes evident following 100 microM SNAP treatments. Damage from 6 h exposures was prevented by the presence of haemoglobin (a NO scavenger), uric acid (a peroxynitrite scavenger), melatonin (a non-specific antioxidant), and by cyclosporin A (a permeability transition pore blocker). It was reduced by the PARP-1 inhibitor 3,4-dihydro-5-[4-(1-piperidinyl)butoxyl]-1(2H)-isoquinolinone (DPQ), whilst superoxide dismutase (SOD) potentiated the effects. Following 24 h exposure to SNAP, damage was only partially blocked by haemoglobin, melatonin, cyclosporin A and DPQ, but was not affected by uric acid or SOD. The data suggest that short exposure to NO induces neuronal damage through peroxynitrite produced by its interaction with superoxide, whereas a longer exposure to NO can induce damage partly by a mechanism which is independent of peroxynitrite formation.
一氧化氮（NO）可诱导细胞增殖或细胞死亡，这取决于所涉及的细胞类型、被激活的一氧化氮合酶同工型及其细胞定位。在神经元中，NO的损伤作用通常归因于其与超氧化物反应形成的剧毒过氧亚硝酸盐。过氧亚硝酸盐会诱导DNA损伤，进而激活聚（ADP - 核糖）聚合酶（PARP）。本研究旨在探讨过氧亚硝酸盐对用NO供体S - 亚硝基 - N - 乙酰青霉胺（SNAP）处理小脑颗粒神经元（CGN）所诱导损伤的作用，处理时间为短期（6小时）或长期（24小时）暴露。使用alamar蓝测定法来量化CGN的活力，也通过形态学检查进行评估。SNAP（10微摩尔 - 1毫摩尔）诱导CGN活力呈浓度和时间依赖性降低，在100微摩尔SNAP处理后，细胞体和神经突明显受损。血红蛋白（一种NO清除剂）、尿酸（一种过氧亚硝酸盐清除剂）、褪黑素（一种非特异性抗氧化剂）和环孢素A（一种通透性转换孔阻滞剂）的存在可防止6小时暴露造成的损伤。PARP - 1抑制剂3,4 - 二氢 - 5 - [4 - （1 - 哌啶基）丁氧基] - 1（2H） - 异喹啉酮（DPQ）可减轻损伤，而超氧化物歧化酶（SOD）则增强了这种作用。在24小时暴露于SNAP后，损伤仅部分被血红蛋白、褪黑素、环孢素A和DPQ阻断，但不受尿酸或SOD的影响。数据表明，短期暴露于NO通过其与超氧化物相互作用产生的过氧亚硝酸盐诱导神经元损伤，而长期暴露于NO可能部分通过一种独立于过氧亚硝酸盐形成的机制诱导损伤。
