Objective      To determine the effect of Bifidobacterium on the intestinal permeability and serum expression of zonulin in neonatal rats with necrotizing enterocolitis (NEC)

and discuss the protective mechanism of Bifidobacterium from NEC.       Methods      According to random number table

60 1-day-old Sprague-Dawley rats were divided into 3 groups: control group

NEC group

and Bifidobacterium intervention group (NEC+BIF group) (n=20). The weights of rats were measured in 3 consecutive days at same time. After day 4

all the rats were put to death

and the proximal intestines of ileocecal junction underwent pathological sectioning. HE staining was carried out to observe histological changes and score the tissue damage. The intestinal permeability was analyzed by fluorescein isothiocyanate dextran (FITC-Dextran) tracing. The serum zonulin was detected by ELISA. The expression and distribution of tight junction proteins (Claudin-1

Occludin

and ZO-1) were analyzed by Western blotting and immunohistochemical assay. Finally

the correlation analysis between the intestinal permeability

the expression of tight junction proteins and the serum level of zonulin was performed.       Results      Compared with the NEC group

the intestinal injury was obviously alleviated after Bifidobacterium intervention. Compared with the control group

the intestinal permeability and the level of zonulin in the NEC group were significantly increased (both P0.05)

and the expression of tight junction proteins (Claudin-1

Occludin

ZO-1) was significantly decreased (P0.05)

with discontinuous distribution. Compared with the NEC group

the intestinal permeability was decreased (P0.05)

the expression of zonulin was significantly decreased (P0.05)

and the expression of tight junction proteins was increased (P0.05) in the NEC+BIF group. The correlation analysis showed that the level of zonulin was positively correlated with the intestinal permeability (r=0.923

P0.01)

and negatively correlated with the expression of tight junction proteins (Claudin-1

Occludin

ZO-1) (r=-0.779

P0.01; r=-0.920

P0.01; r=-0.619

P0.01).       Conclusion      Bifidobacterium can improve the intestinal permeability in the neonatal rats with NEC

and the mechanism may be related with inhibition of zonulin expression.