黄嘌呤氧化酶在新生鼠坏死性小肠结肠炎中的作用

Roles of xanthine oxidase in necrotizing enterocolitis in the newborn rat

摘要:

目的：坏死性小肠结肠炎是新生儿常见的严重胃肠道疾病。活性氧与其发生密切相关,而黄嘌呤氧化酶是活性氧的主要来源。该研究采用新生鼠坏死性小肠结肠炎模型,探讨黄嘌呤氧化酶与肠损伤的关系。方法：48只新生大鼠,随机分为对照组8只,实验组40只,每一时相点8只。将大肠杆菌O55:B5 脂多糖5mg/kg用无菌生理盐水稀释至0. 2mL注入实验组新生鼠胃内,分别于注入后3, 6, 12, 24, 72h处死动物,分离胃肠道。对照鼠予以0. 2mL无菌盐水灌胃, 3h后处死,取部分回肠末端组织固定,包埋,苏木精伊红染色,光镜下观察其组织学改变,进行评分。其余回肠组织用于测定黄嘌呤氧化酶活性,并与组织学评分进行相关性分析。结果：实验组3, 6, 12, 24h肠损伤评分分别为1. 54±0. 87, 1. 79±0. 75, 1. 92±0. 43, 2. 29±0. 60,均明显高于对照组( 0. 08±0. 15) (均P<0. 05);黄嘌呤氧化酶活性分别为1. 15±0. 09, 1. 24±0. 15, 1. 30±0. 18, 1. 42±0. 21U/mgprot,亦显著高于对照组(0. 95±0. 13U/mgprot) (P<0. 05)。24h内黄嘌呤氧化酶活性的高低与平均肠损伤程度呈显著正相关。结论：黄嘌呤氧化酶可能是引起坏死性小肠结肠炎的重要酶。

Abstract:

OBJECTIVE: Necrotizing enterocolitis (NEC) is a common severe gastrointestinal disorder in premature infants. Reactive oxygen species (ROS) has been proved to have a close relationship with the pathogenesis of NEC. This study aimed to explore the relationship between xanthine oxidase (XO), one of the major sources of ROS, and intestinal injury using a neonatal rat model of NEC. METHODS: Forty-eight newborn rats were assigned randomly into two groups: NEC group (n=40, 8 each time point) and Control group (n=8). The rats of the NEC group were given gastric lavage with 5 mg/kg E coli O_ 55∶B_5 endotoxin (LPS) dissolved in 0.2 mL normal saline. The rats of the Control group received gastric lavage treatment with 0.2 mL normal saline alone, and were sacrificed 3 hrs later. The NEC rats were sacrificed 3, 6, 12, 24, and 72 hrs after treatment respectively. A part of lower ileum was removed, fixed, embedded in paraffin.and stained with hematoxylin and eosin for histological evaluation. The rest of the ileum was frozen in liquid nitrogen for XO activity measurements. The correlation between the histological changes and XO activity was studied. RESULTS: The intestinal injury scores were significantly higher in the NEC group 3, 6, 12 and 24 hrs after treatment (1.54±0.87, 1.79±0.75, 1.92±0.43 and 2.29±0.60) than that of the Control group (0.08±0.15) (P<0.05). Increased XO levels were observed in the NEC group at each time point (1.15±0.09, 1.24±0.15, 1.30±0.18 and 1.42±0.21 U/mgprot) when compared with that of the Control group (0.95±0.13 U/mgprot) (P<0.05). Spearman correlation analysis showed a significantly positive correlation between XO levels and intestinal injury scores within 24 hrs of LPS treatment . CONCLUSIONS: XO may play an important role in the development of necrotizing enterocolitis.