Miller M J, Thompson J H, Zhang X J, Sadowska-Krowicka H, Kakkis J L, Munshi U K, Sandoval M, Rossi J L, Eloby-Childress S, Beckman J S
Department of Pediatrics, Louisiana State University Medical Center, New Orleans, USA.
Gastroenterology. 1995 Nov;109(5):1475-83. doi: 10.1016/0016-5085(95)90633-9.
BACKGROUND & AIMS: Inflammatory bowel disease is characterized by increased synthesis of nitric oxide. The aim of this study was to determine if inducible NO synthase (iNOS) was responsible for tissue injury, potentially via peroxynitrite formation, in the guinea pig model of gut inflammation.
Inflammation was induced in guinea pig ileum by intraluminal administration of the hapten trinitrobenzene sulfonic acid in 50% ethanol. iNOS gene expression was assessed by reverse-transcriptase polymerase chain reaction and Western blotting, immunohistochemistry was determined by its localization, and activity was inhibited with the specific inhibitor aminoguanidine administered via the drinking water for 7 days. Nitration of tyrosines was assessed by immunohistochemistry.
In control animals, iNOS gene expression was minimal to absent, whereas, in hapten, inflammation-marked iNOS gene expression was evident from day 1 to 7. Nitrotyrosine and iNOS immunohistochemistry were colocalized, and positive staining was most intense in epithelia and neurons. Inhibition of NO formation prevented nitrotyrosine formation. Aminoguanidine inhibited the inflammatory response and restored morphology.
The colocalization of tyrosine nitration with iNOS immunoreactivity suggests that iNOS may be responsible for tissue injury and the formation of NO-dependent nitrating species, potentially peroxynitrite. Inhibition of iNOS may afford a new therapeutic approach to the treatment of inflammatory bowel disease.
炎症性肠病的特征是一氧化氮合成增加。本研究的目的是确定在豚鼠肠道炎症模型中，诱导型一氧化氮合酶（iNOS）是否通过过氧亚硝酸盐的形成导致组织损伤。
通过向豚鼠回肠腔内注射50%乙醇中的半抗原三硝基苯磺酸诱导炎症。通过逆转录聚合酶链反应和蛋白质免疫印迹法评估iNOS基因表达，通过其定位确定免疫组织化学，并通过饮用水给予特异性抑制剂氨基胍7天来抑制其活性。通过免疫组织化学评估酪氨酸的硝化作用。
在对照动物中，iNOS基因表达极少或不存在，而在半抗原诱导的炎症中，从第1天到第7天iNOS基因表达明显。硝基酪氨酸和iNOS免疫组织化学共定位，上皮细胞和神经元中的阳性染色最强。一氧化氮形成的抑制可防止硝基酪氨酸的形成。氨基胍抑制炎症反应并恢复形态。
酪氨酸硝化与iNOS免疫反应性的共定位表明，iNOS可能导致组织损伤和形成一氧化氮依赖性硝化物质，可能是过氧亚硝酸盐。抑制iNOS可能为炎症性肠病的治疗提供一种新的治疗方法。
