Effects Of Exogenous Epidermal Growth Factor On Repair Of Premature Intestinal Mucosa With Necrotizing Enterocolitis

Subject:To investigate the effects of exogenous Epidermal Growth Factor(EGF) on repair of premature intestinal mucosa with Necrotizing Enterocolitis(NEC).Method:Thirty 1 day neonatal rats were devided into three groups randomly:group A(control group),group B(NEC model),group C(NEC+EGF 200μg/kg·d).NEC model was established as following method:neonatal rats were put into 100%nitrogen for 90s and into 4℃for 10min.After NEC model of neonatal rats,all the neonatal rats were returned to their mothers and feed with breast milk.This was done twice daily for 3days.In the 4^th day, all the subjects were put to the death.Intestinal tissue located at the boundary of ileum and cecum was obtained to observe pathological study and histological changes.Morphological changes were measured under a light microscope,and expression of proliferating cell nuclear antigen(PCNA) as an index of cell proliferation was observed using immunohistochemical staining and image analysis,expression of apoptosis was observed by TUNEL staining and image analysis.EGFR mRNA content of the intestinal cells were quantitited by real time PCR.Result:In group B and group C,the histological lesions ranged graded differently.Some intestinal mucousa was normal,and some stratum submucosum and lamina propria was separate,or stratum submucosum and basement layer was dropsy.The number of PCNA positive cells in group B was significantly lower than that in group A(P=0);The number of PCNA in group C was higher than that in group B(P=0.017).The number of apoptosis positive cells in group B was significantly higher than that in group A(P=0);The number of apoptosis in group C was lower than those in group B(P=0.017).NEC induced a marked reduction in the EGFR mRNA expression in the intestinal mucosa(P=0.029).But the EGFR mRNA expression in the intestinal mucosa obviously increased when EGF was administered with NEC(P=0.042),but bore no significant difference between group A and group C(P=0.745).Conclusions:NEC can damage neonate rats' intestinal mucosa,step down proliferation of intestinal mucosa,and to increase cell apoptosis in intestinal mucosa.EGF can improve the proliferation of crypt cell,reduce apoptosis of intestinal mucosa,and promote repair of intestinal mucosa after NEC.EGF might enhance the expression of EGFR in the intestinal mucosa.