早产大鼠坏死性小肠结肠炎三种常用模型的建立及评价

目的 用人工喂养+缺氧+冷刺激、缺氧-复氧及腹腔注射内毒素(lipopolysaccharides,LPS)等国内外常用方法建立早产大鼠坏死性小肠结肠炎(necrotizing enterocolitis,NEC)模型,并进行比较和评价. 方法 A组早产大鼠(n=10)采用代乳品人工喂养,并给予100%氮气缺氧90 s,4℃冷刺激10 min,每天2次,连续2 d;B组早产大鼠(n=10)给予100%氮气5 min,100%氧气5 min,每天2次、连续3 d;C组早产大鼠(n=10)给予腹腔注射LPS 5 mg/kg;D、E、F组为相应正常对照组,每组10只.HE染色后光镜下观察肠道、肝、肺及肾组织病理改变,并对肠组织损伤情况进行病理评分,评分≥2分确定为NEC. 结果 A、B、C组均出现不同程度的活动减少,腹胀腹泻,肠道扩张充血.A至F组的肠组织损伤病理评分结果分别为(3.13±0.64)分、(1.40±0.52)分、(2.00±0.42)分、(0.30±0.48)分、(0.30±0.48)分和(0.40±0.52)分,模型组与相应对照组比较,差异有统计学意义(P＜0.01);模型组内B组与A组比较,差异有统计学意义(P＜0.01);C组与A组比较,差异亦有统计学意义(P＜0.05).A、B、C组的NEC发生率分别为6/8、20%(5/10)和4/8,对照组的NEC发生率均为0.C组的肝脏、肾脏和肺脏损伤较A、B组严重,而对照组各重要脏器均未见异常. 结论与缺氧-复氧和腹腔注射LPS等单因素的建模方法相比,综合运用人工喂养+缺氧+冷刺激更接近新生儿NEC的病因,且其发生率高,重复性好,特异性强,是一种较为理想的NEC建模方法.

Comparison of different methods in the establishment of necrotizing enterocolitis models in premature rats

Objective To establish and evaluate three different necrotizing enterocolitis models,established by combination of formula feeding, hypoxia and cold exposure, hypoxia-reoxygenation, and intraperitoneal injection of lipopolysaccharides (LPS) in premature rats. Methods Group A was given formula feeding, hypoxia by exposing to 100% N2 for 90 s and 4 ℃ cold stress for 10 minutes, the hypoxia and cold stress were given twice a day for 2 d. Group B was put into 100% N2 for 5 min and then 100% O2for 5 min, twice a day for 3 d. Group C was injected intraperitoneally 5 mg/kg LPS. Group D, E and F were served as the corresponding controls for group A, B and C. Ileocecal junction, liver, kidney and lung tissues were harvested and evaluated by HE staining for histological analysis, histological changes of ileal tissues were scored, and rats with score higher than two were diagnosed with NEC. Results Premature rats in group A, B and C showed various degrees of decreasing activity, abdominal distention, diarrhea,intestinal dilatation and congestion. Histological score in group A to F were 3. 13 ± 0. 64, 1.40 ±0. 52,2. 00±0. 42,0. 30±0. 48, 0. 30±0. 48 and 0. 40±0. 52, respectively. There were significant differences between model groups and their corresponding control groups (P＜0. 01 ). Among the model groups, the histological score of group A was higher than group B (P＜0.01) and group C (P＜0.05). The incidences of NEC in group A, B and C were 6/8, 20% (5/10) and 4/8, respectively, while of zero in all control groups. Liver, kidney and lung injures were more serious in group C compared with the other groups.Conclusions Compared with the single-factor modeling approaches of intraperitoneal injection of LPS and hypoxiareoxygenation, the NEC animal model in preterm rats established by formula feeding, repeated hypoxia and cold exposure, is more similar to the etiological factors of neonatal NEC in human, with higher incidence, better reproducibility and specificity.