Effects of heparin-binding epidermal growth factor-like growth factor on mitochondrial pathway of apoptosis in neonatal rats with necrotizing enterocolitis / 中华围产医学杂志

ABSTRACT

Objective To investigate the effect of heparin-binding epidermal growth factor-like growth factor (HB-EGF) on mitochondrial pathway of apoptosis in rats with neonatal necrotizing enterocolitis (NEC).Methods Sprague-Dawley neonatal rats were randomly divided into three groups with ten in each.NEC group rats were formula fed,and hypoxia exposed by 100％ N2 for 90 s and cold stress at 4 ℃ for 10 min twice a day for three days.Additionally,rats in HB-EGF group received HB-EGF 800μg/kg by gavage four times a day for three days.Rats in control group were given breast milk feeding for three days without any interventions.Seventy-two hours after born,all neonatal rats were sacrificed after fasting for 12 h,from which the terminal ileum was removed.HE-staining was done for histologic evaluation.Mitochondrial ultrastructure was observed under electron microscopy.Cytochrome C was detected by immunohistochemical analysis and apoptosis inducing factor (AIF) and apoptotic protease activating factor-1 (APAF-1) were measured by Western blot.Analysis of variance and q-test were used to compare the difference among groups.Results (1) The incidence of NEC in HB-EGF group was lower than that in NEC group (2/10 vs 9/10,x2 =7.27,P＜0.01).(2) In NEC group,mitochondria in epithelial cells and muscle cells of intestine were significantly swelling,appearing many electron-lucent zones in matrix.Ultrastructure of mitochondria were severely damaged.In HB-EGF group,mitochondria were less swelling and showed milder damage than those in NEC group.(3) The expression of cytochrome C in ileal tissue in NEC group was higher than that in control group (0.030±0.018 vs 0.002±0.001,q=6.15,P＜0.01).The expression of cytoehrome C in ileal tissue in HB-EGF group was lower than that in NEC group (0.014±0.018 vs 0.030±0.018,q=3.53,P＜0.05).The expression of APAF-1 and AIF in NEC group was higher than those in control group (1.364±0.299 vs 0.215±0.033,q=15.31,P＜0.05;0.181±0.050 vs0.127±0.045,q=3.71,P＜0.05).Compared to NEC group,the expression of APAF-1 was lower (0.455±0.123 vs 1.364±0.299,q=4.04,P＜0.05) and the expression of AIF was higher (0.289±0.045 vs 0.181±0.050,q=7.32,P＜0.05) in HB-EGF group.Conclusions HB-EGF could reduce the incidence of NEC in neonatal rats by inhibiting the mitochondrial pathway related apoptosis through down regulation of APAF-1.