Kumral Abdullah, Baskin Hüseyin, Duman Nuray, Yilmaz Osman, Tatli Mansur, Ozer Erdener, Gökmen Necati, Genc Sermin, Ozkan Hasan
Department of Pediatrics, School of Medicine, Dokuz Eylul University, Izmir, Turkey.
Biol Neonate. 2003;84(4):325-9. doi: 10.1159/000073642.
Necrotizing enterocolitis (NEC) is an important neonatal disease with a high mortality rate; erythropoietin (Epo) is a hematopoietic growth factor. Functional Epo receptors are in the fetal and postnatal small bowel and their ligands are available for binding. Excessive nitric oxide (NO) production by an isoform of NO synthase inducible by inflammatory stimuli leads to changes in vascular permeability and tissue injury. The aim of this study was to investigate NO formation in an experimental model of NEC and the possible role of NO in the protection Epo provides against NEC.
Twenty-four Wistar albino rat pups were divided into three groups: group 1 = control; group 2 = hypoxia-reoxygenation and saline; group 3 = hypoxia-reoxygenation and recombinant human EPO (rhEpo) pretreatment. rhEpo was given 750 U/kg/week by intraperitoneal injection 3 times a week for 2 weeks. On the 15th day, hypoxia was induced by placing the pups in a 100% CO(2) chamber for 5 min. After the hypoxia period the pups were reoxygenated for 10 min with 100% O(2) and returned to their mothers. All pups were killed 4 h after the hypoxia-reoxygenation period was over. The abdomen was opened and representative samples of injured areas were taken for histopathologic examination. Then nitrite levels were determined in the intestine by Griess Reagent.
On histopathological examination, injury scores in group-2 animals were found to be significantly higher than in group-3 animals (p = 0.001). Significantly increased intestinal nitrite levels were found in group-2 rats compared to the rats of groups 1 and 3 (p = 0.001 and p = 0.001, respectively). There was a positive correlation between the histological findings and the intestinal nitrite levels in group-2 and -3 animals (r = 0.94, p = 0.001; r = 0.99, p = 0.001, respectively).
The present study demonstrates that the Epo-pretreated group had decreased levels of NO and limited mucosal necrosis in intestinal tissue samples. We believe that these results deserve further experimental studies in order to elucidate the possible effector mechanisms involved in the inhibitory relationship between Epo, NO and NEC.
坏死性小肠结肠炎（NEC）是一种死亡率很高的重要新生儿疾病；促红细胞生成素（Epo）是一种造血生长因子。功能性Epo受体存在于胎儿和出生后的小肠中，且其配体可供结合。炎症刺激诱导的一氧化氮合酶同工型产生过量一氧化氮（NO）会导致血管通透性改变和组织损伤。本研究的目的是调查NEC实验模型中NO的形成以及NO在Epo对NEC的保护作用中可能发挥的作用。
将24只Wistar白化病幼鼠分为三组：第1组 = 对照组；第2组 = 缺氧-复氧及生理盐水组；第3组 = 缺氧-复氧及重组人促红细胞生成素（rhEpo）预处理组。rhEpo通过腹腔注射，剂量为750 U/kg/周，每周3次，共2周。在第15天，将幼鼠置于100% CO₂ 舱中5分钟以诱导缺氧。缺氧期过后，幼鼠用100% O₂ 复氧10分钟，然后放回母鼠身边。在缺氧-复氧期结束4小时后处死所有幼鼠。打开腹腔，取损伤区域的代表性样本进行组织病理学检查。然后用格里斯试剂测定肠道中的亚硝酸盐水平。
组织病理学检查发现，第2组动物的损伤评分显著高于第3组动物（p = 0.001）。与第1组和第3组大鼠相比，第2组大鼠肠道中的亚硝酸盐水平显著升高（分别为p = 0.001和p = 0.001）。第2组和第3组动物的组织学结果与肠道亚硝酸盐水平之间存在正相关（分别为r = 0.94，p = 0.001；r = 0.99，p = 0.001）。
本研究表明，rhEpo预处理组肠道组织样本中的NO水平降低，黏膜坏死受限。我们认为，这些结果值得进一步进行实验研究，以阐明Epo、NO和NEC之间抑制关系中可能涉及的效应机制。
