Objective:To establish a new animal model of neonatal necrotizing enterocolitis (NEC) by cold exposure after hypoxic-reoxygenation treatment

formula feeding and (Lipopolysaccharid

LPS)intragastric administration on the base of the modeling status

and to compare the differences between them. Methods:According to different modeling methods

0-day-postnatal S-D rats were divided into 6 groups randomly

each group including 8 rats. Group A was given cold exposure shortly after hypoxic-reoxygen treatment and received formula feeding. Group B was in the same condition expect extra LPS intragastric administration. Group C was given cold exposure after simple hypoxic-reoxygenation treatment. Group D received LPS intragastric administration. Group E was given formula feeding alone. Group F was set up as control group. All rats were weighed every day and sacrificed on the 4th day. Proximal intestines of ileocecal junction were harvested and were evaluated by HE staining for pathological scoring. Results:All the neonatal rats in model groups had physical inactivity

abdominal distention and a change in stool. On day 3

neonatal rats in group A

B

and E had weight loss

while group C

D

and F had weight gain. The terminal weight and weight change of every model group were different from that of Group F (P<0.05). ByKruskal-wallis analysis

weight changes ofeach group were:Group F>Group D>Group C>Group E> Group A>Group B. The pathological scores (x±s)for each gourp were group A:3.0±0.53

group B:3.63±0.52

group C:1.75±0.71

group D:1.75±0.46

group E:2.38±0.52 and group F 0.5±0.53 respectively. The score of group B had significant differences from those of other 5 groups (P<0.05). Cold exposure after hypoxic-reoxygenation

formula feeding and LPS intragastric administration were all risk factors for NEC. Our newmethod with combination of all these factors could produce the most serious intestine injury. Conclusions:By cold exposure after hypoxic-reoxygenation

formula feeding and LPS intragastric administration

we could produced animal models which had intestine injurysimilar to neonatal necrotizing enterocolitis. This new method could be used for the establishment of NEC animal modle extensively.