Establishment And Evaluation Of Neonatal Necrotizing Enterocolitis Models

Objective:Research the potential of dextran sulfate sodium(DSS)establishing necrotizing enterocolitis(NEC)model in neonatal rats to provide a practical experimental method for further research on the pathogenesis and control scheme of neonatal necrotizing enterocolitis.Methods:Newborn pups of rats on the day of birth were randomly divided by a ratio of 2:1:6 intocontrol group(n=24),LPS treat group(n=12)and DSS treat group(n=72)which was randomly divided into five subgroups that respectively correspond to 1%to 5%(m/v)DSS.The bodyweight was weighed regularly,and the growth and development of all neonatal rats such as the condition of survival and activity as well as mental state were closely observed during experiment.The proximal ileocecal andgeneral situation of intestine of neonatal pups werecompared respectively under light microscope andnaked eye after euthanized.The inflammatory factors of intestinal were detected by qRT-PCR and ELISA.According to the pathological scoring standard of Nadeler et al.,the pathological score?2 were considered to have developed NEC.Result:The survival rate of control group and LPS treat group as well as DSS(2%)treat group were 100%,90.90%,66.70%respectively.The body weight of DSS(2%)treat group was significantly lower than that of control group and LPS treat group(P<0.05),but there was no significant difference in control group and LPS treat group(P>0.05).Neonatal rats in control group had good growth and development and active and sensitive response.In LPS treat group,the activity was slightly reduced,and there was response to mild or moderate stimulation.However,DSS(2%)treat groups had significantly reduced activity even completely still and poor or no reaction to stimuli.The clinical sickness score of DSS(2%)treat group and LPS treat group were significant difference with control group,and the clinical sickness score of DSS(2%)treat group was significantly higher than LPS treat group(P<0.05).We found the intestinal tract in control group was basically normal and had no obvious changes.The intestinal specimens ofDSS(2%)treat group and LPS treat group shown dilation of whole and partial intestinal segments)bleeding and gas accumulation in intestinal with varying degrees of color change,especially the most severe lesions in the ileocecal proximal and severe bead-like changes were observe in DSS(2%)treat group.The gross intestinal score of LPS treat group and DSS(2%)treat group showed significant difference with control group(P<0.05),and DSS(2%)treat group was higher than LPS treat group(P<0.05).We found control group was normal,intestinal villous lesions were apparent in other groups.The pathological injury score of DSS(2%)treat group and LPS treat group were significantly different from control group(P<0.05),and DSS(2%)treat group was higher than LPS treat group(P<0.05).NEC-like intestinal injury criterion refers to Nadler's standard(pathological score?2).The incidence of NEC was 0.00%in control group,LPS treat group and DSS(2%)treat group was 45.45%and 80.00%respectively.Compared with control group,the expression levels of inflammatory factors including CXCL1,CXCL2,IL-6 and TNF-? in the other groups were significantly increased,and we found DSS(2%)treat group significantly higher than LPS treat group(P<0.05).Conclusion:Dextran sodium sulfate can successfully induce severe intestinal injury that basically consistent with the clinical characteristics and pathological changes of neonatal necrotizing enterocolitis in neonatal rats.And the DSS with the concentration of 2%(m/v)was the best suited for research of neonatal necrotizing enterocolitis because of the advantages of high success rate,excellent specificity,stability and repeatability.