Abstract 【Abstract】 Objective To establish and evaluate the effect of the neonatal necrotizing enterocolitis (NEC)model induced by lipopolysaccharide (endotoxin, LPS) combined with formula feeding. Method According todifferent modeling methods, 0-day-postnatal SD rats were divided into 9 groups randomly, each group including 8 rats. Group A was given formula feeding alone; group B1, B2, B3, B4, B5 and B6 were given formula feeding and LPS intragastric administration, the dosages of LPS were respectively 5, 10, 15, 20, 30, 40 mg/kg in order to screen out the best one; group C was given breast feeding and LPS intragastric administration; group D was set up as control group and given breast feeding only. All rats were weighed every day at regular time. After 3 days feeding and fasting for 24 hours and then all the rats had been sacrificed. Terminal ileum were harvested and observed the intestinal histopathological damage by HE staining, and evaluated the ileal damage by pathological score. The rats with pathological score higher than two were defined as NEC. According to the modeling method of group B5, repeated twice, 8 rats each time, and divided into group B5a and B5b. Result Neonatal rats in group A, B4, B5 and B6 showed various degrees of physical inactivity, tiredness, and then abdominal distention and changes of stool’s color and character. On day 3, the weight of neonatal rats in group A and B had no
increase or even loss, and group C and D had weight gain. The terminal weights and weight changes of group A and B were significantly different from that of Group C and D (P<0.05). The pathological score of every group were respectively: group A:1.78±0.52, group B1: 1.76±0.32, group B2: 1.83±0.1, group B3: 1.87±0.33, group B4: 2.16±0.11, group B5: 3.34±0.37, group B6: 3.78±0.51, group C: 0.52±0.42, group D: 0.3±0.48. There were significant differences between model groups B5, B6 and control group D (P<0.05). Among the model groups, the pathological scores of group B5, B6 were significantly higher than group B1, B2, B3 and B4 (P<0.05). There were significant differences between model groups B5, B6 and group A (P<0.05). There were no significant differences between model groups B5a, B5b and group B5. The incidences of NEC in group B4, B5 and B6 respectively were 25%(2/8）, 75％(6/8) and100%（8/8）. While the incidences of NEC in group A, B1, B2, B3, C and D were all zero.
Conclusion When the dosage of LPS was 30mg/kg and combined with formula feeding could induced serious intestinal damage, which had almost the same clinical features and pathological changes as human neonatal NEC. This modeling method has high incidence, good repeatability and high specificity, which could be used in the research of neonatal NEC.
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2014, Vol. 2 
