Effect Of Bifidobacterium On The Intestinal Injury In Neonatal Rat With Necrotizing Enterocolitis

Objective To determine the effects of bifidobacterium on the intestinal injury in neonatal rat with necrotizing enterocolitis(NEC), and to discuss the protective mechanism of bifidobacterium on NEC.Methods 120 one-day-old Sprague-Dawley rats were divided into three groups according to random number table method: a control group, a necrotizing enterocolitis group(NEC group), and a bifidobacterium intervention group(NEC+BIF group)(n=40 per group). The weights of rats were measured in three days at same time. The genenal condition of rats were observed, and the mortality and the incidence rate of NEC were calculated in the experiment. After 4 days, all the subjects were put to death and proximal intestines of ileocecal junction were undertaken pathological sectioning. HE dyeing was carried out to observe histological changes and make a score of tissue damage. The intestinal permeability was analyzed by fluorescein isothiocyanate dextran(FITC-Dextran). The serum level of Zonulin was detected by ELISA. The expression and distributin of tight junction protein were analyzed by western blotting andimmunohistochemical method. Finally we performed the correlation analysis between the intestinal permeability and the expression of tight junction protein(Claudin-1, Occludin, ZO-1) and the level of Zonulin. The statistical analyses were performed with SPSS software version 19.0. The data are presented as the means ± standard deviation. An ANOVA with Bonferroni’s post-test or a Student’s t-test was performed. The categorical data were analyzed using the Chi-squared test. Correlation analyses were performed using the Pearson’s test. P<0.05 was considered to be statistically significant.Results Compared with NEC group, the mortality and the incidence rate of NEC were significantly decreased, and the intestinal injury was obviously alleviated after bifidobacterium intervention. Compared with control group, the intestinal permeability was significantly increased(P<0.05), the level of zonulin significantly increased(P<0.05), the expression of tight junction protein(Claudin-1, Occludin, ZO-1) significantly decreased(P < 0.05) and whose distribution is also discontinuous in the NEC group. Compared with NEC group, the intestinal permeability was decreased(P<0.05), the expression of Zonulin significantly decreased(P<0.05), the expression of tight junction protein increased(P < 0.05). The correlation analysis showed that the level of Zonulin were obviously positively correlated with the intestinal permeability(r=0.923, P < 0.01),and negatively correlated with the expression of tight junction protein(Claudin-1, Occludin, ZO-1)(r=- 0.779, P < 0.01; r=- 0.920, P < 0.01;r=- 0.619, P<0.01).Conclusion Established a stable necrotizing enterocolitis neonatal rat model; The necrotizing enterocolitis neonatal rats had obviously intestinal injury, and the level of serum Zonulin and the intestinal permeability were increased in these rats; Bifidobacterium could protect intestinal injury in the necrotizing enterocolitis neonatal rats; The protective mechanism of bifidobacterium on the necrotizing enterocolitis neonatal rats may include inhibiting serum Zonulin release, improving the expressions and distribution of the tight junction proteins and alleviating intestinal permeability.