Ozen Samim, Akisu Mete, Baka Meral, Yalaz Mehmet, Sozmen Eser Yildirim, Berdeli Afig, Kultursay Nilgun
Department of Pediatrics, Ege University Medical School, Bornova, TR-35100 Izmir, Turkey.
Biol Neonate. 2005;87(2):91-6. doi: 10.1159/000081897. Epub 2004 Nov 3.
Necrotizing enterocolitis (NEC) is a potentially lethal disease among premature infants. The aim of the present study was to investigate whether hypoxia-reoxygenation (H/R)-induced intestinal injury was due to increased apoptosis of the intestinal mucosa in young mice and whether pre-treatment of the animals with recombinant human insulin-like growth factor-I (IGF-I), a known anti-apoptotic factor, could protect the intestinal cells from H/R-induced apoptosis or intestinal injury.
Young mice were divided into three groups: group 1 mice (H/R) were hypoxia-reoxygenation; group 2 mice (H/R + IGF-I) were treated with recombinant human IGF-I by intraperitoneal injection (1 mug/g b.w. once daily) for 7 days, and group 3 mice served as control. Hypoxia was induced by placing young mice in a Plexiglas chamber consisting of 10% oxygen for 60 min. After hypoxia, the young mice were reoxygenated for 10 min with 100% oxygen. Intestinal generation of substances reactive to thiobarbituric acid (TBARS) and active caspase-3 were measured in H/R-induced intestinal injury.
Increased numbers of apoptotic cells (apoptotic index) across the villi in young mice subjected to H/R were observed with the TUNEL reaction whereas few apoptotic cells existed in the control animals. In addition, H/R-induced intestinal damage in the H/R + IGF-I group was greatly attenuated, with necrosis limited partially to the mucosa. Tissue-active caspase-3 levels in the H/R group were found to be significantly higher when compared with that of the H/R + IGF-I group of mice and control. However, TBARS concentrations in the intestine were similar in H/R groups when compared to the intestine of control animals.
The present study suggests that both necrosis and apoptosis, via mechanisms occurring due to oxygen-derived free radicals and activation of caspase-3, play a role in the pathogenesis of H/R-induced bowel injury. We also show that IGF-I protect intestinal mucosa from necrosis and apoptosis from intestinal H/R injury.
坏死性小肠结肠炎（NEC）是早产儿中一种具有潜在致命性的疾病。本研究的目的是调查低氧复氧（H/R）诱导的肠道损伤是否是由于幼鼠肠黏膜凋亡增加所致，以及用重组人胰岛素样生长因子-I（IGF-I，一种已知的抗凋亡因子）对动物进行预处理是否能保护肠道细胞免受H/R诱导的凋亡或肠道损伤。
将幼鼠分为三组：第1组小鼠（H/R组）进行低氧复氧处理；第2组小鼠（H/R + IGF-I组）通过腹腔注射重组人IGF-I（1μg/g体重，每日一次）处理7天，第3组小鼠作为对照。通过将幼鼠置于含10%氧气的有机玻璃箱中60分钟来诱导低氧。低氧后，幼鼠用100%氧气复氧10分钟。在H/R诱导的肠道损伤中测量肠道中对硫代巴比妥酸（TBARS）有反应的物质生成和活性半胱天冬酶-3。
通过TUNEL反应观察到，H/R处理的幼鼠整个绒毛的凋亡细胞数量增加（凋亡指数），而对照动物中几乎没有凋亡细胞。此外，H/R + IGF-I组中H/R诱导的肠道损伤大大减轻，坏死部分局限于黏膜。发现H/R组的组织活性半胱天冬酶-3水平与H/R + IGF-I组小鼠和对照组相比显著更高。然而，与对照动物的肠道相比，H/R组肠道中的TBARS浓度相似。
本研究表明，坏死和凋亡通过氧衍生自由基和半胱天冬酶-3激活所发生的机制，在H/R诱导的肠损伤发病机制中起作用。我们还表明，IGF-I可保护肠黏膜免受坏死以及肠道H/R损伤诱导的凋亡。
