一氧化氮在结肠黏膜上皮细胞氧化损伤中的作用观察

目的探讨一氧化氮（NO）在结肠黏膜上皮细胞氧化损伤中的作用及褪黑素的影响。方法利用FeSO4＋H2O2产生羟自由基损伤结肠黏膜上皮细胞，观察L-精氨酸、L-NAME对模型中NO合成的影响及相应细胞损伤程度的改变，并观察褪黑素对该过程的影响。实验检测指标包括乳酸脱氢酶（LDH）、丙二醛（MDA）、谷胱甘肽过氧化物酶（GSHPx）、过氧化氢酶（CAT）、超氧化物歧化酶（SOD）、NO和黏液含量。结果模型组大鼠结肠黏膜上皮细胞MDA和LDH水平增高，CAT、GSHPX、SOD和黏液含量减少，NO水平增高与结肠黏膜上皮细胞氧化损伤相关，L-精氨酸和L-NAME通过促进或抑制NO合成，显著加重或减轻这种氧化损伤。褪黑素可逆转羟自由基及NO引起的氧化损伤。结论NO直接参与羟自由基对结肠黏膜上皮细胞的氧化损伤，褪黑素通过直接清除羟自由基和NO及可能形成的过氧化亚硝基阴离子，对大鼠结肠黏膜氧化损伤具有保护作用。

Effects of nitric oxide on oxidative injury of colonic mucosal epithelial cells induced by hydroxyl radical

Objective To investigate the pathogenesis role of nitric oxide(NO) on the oxidative injury of colonic mucosal epithelial cells induced by hydroxyl radical and the effects of melatonin on this oxidative injury. Methods The oxidative injury model of colonic mucosal epithelial cells was produced by hydroxyl radical generated from the Fenton reaction. L-Arginine was used to increase NO levels while L-NAME lowered its levels in the oxidative injury model, and the effects of melatonin on this model were also observed. At the end of the experiment, the content of lactic dehydrogenase(LDH), malondiadehyde (MDA), glutathione peroxidase(GSHPx), catalase (CAT), superoxide dismutase (SOD), NO and mucus in the supernatant were detected. Results The content of LDH and MDA elevated while the content of GSHPx, CAT, SOD and mucus reduced in model group, particularly contents of NO increased in parallel with the degree of oxidative injury of the colonic mucosal epithelial cells. NO production which enhanced by L-Arginine while inhibited by L-NAME, significantly strengthened or ameliorated this oxidative injury. Melatonin inversed this oxidative injury caused by hydroxyl radical combined with NO. Conclusion Data show that NO directly plays a role in oxidant injury of colonic mucosal epithelial cells induced by hydroxyl radical. As one of the strongest scavengers of hydroxyl radical, NO and peroxynitrite probably form in the course of cellular oxidative reaction. Melatonin has protective effects on rat colon mucosal oxidative injury.