| Objective: Study the change of phospholipase A2 (sPLA2) density in neonatal rat model of necrotizing enterocolitis, and analyses the correlation between the sPLA2 level and the scoring of intestinal injury. Methods: 20 neonate Sprague-Dewley rats(48 hours olds, weighing 5～10g) were divided into two groups(n=10 rats each groups). Model group was made into NEC models as follows: separate from mother rats and feeding with rat milk substitute, hypoxia(100%N2) for 90 second and 4℃cold exposure for 10 minutes, twice a day during 3 consecutive days; Control group was given rat milk feeding, not hypoxia and cold exposure. On the 4th day all the subjects were sacrificed and the intestine around ileocecal junction were obtained to evaluated by stained with H&E for histological analysis and score. The mean scores more than 2 were considered NEC. The contents of PLA2 in homogenate of intestinal tissue were measured by ELISA, and were expressed pg per mg protein of intestinal tissue. Kruskal-Wallis H test, Spearman correlation analysis were used to analyze difference among various groups.α=0.05 was considered significant. Results: Neonatal rats in model group had diarrhea, abdominal distention, growth and development stepping down, activity reducing, and rats in control group was the normal. The scores of histological evaluation (?x±s ) in model group and control group were 3.25±0.85,0.45±0.51, respectively. The score of histopatholigical had significant difference between model group and control group, H=111.419, P=0.000. In model group and control group, the contents of PLA2 in intestinal tissue were 21.752±0.483,0.669±0.180, respectively. Comparing with control group, the contents of PLA2 increased significantly in model group. By spearman correlation analysis, the relations of the degree of intestinal injury and the contents of PLA2 in intestinal tissue were positive(rsPLA2=0.834, P<0.05). Conclusions: Endogenous PLA2 in intestine tissue are probably the critical/key factors for the development of NEC, As risk factors ,themselves take part in the development of NEC. which indicated that the concentrations of sPLA2 in intestine tissue had a positive correlation with the severity of NEC. The concentrations of sPLA2 in intestine tissue can inflect the degree of intestine mucosa lesions. Objective To explore the protective effects and the mechanism of smectite powder in inhibit intestinal injury of neonatal Sprague-Dewley rat necrotizing enterocolitis(NEC) model.Methods According to 2×2 factor analysis, 32 neonate Sprague-Dewley rats(48 hours olds, weighing 5～10g) were divided into 4 groups(A1B1, A1B2, A2B1 and A2B2, n=8 rats each groups). Rats in group A1B1 and A1B2 were made into NEC models as follows: separate from mother rats and feeding with rat milk substitute, hypoxia(100%N2) for 90 second and 4℃cold exposure for 10 minutes, twice a day during 3 consecutive days. Rats in group A1B1 was given smectite powder(0.6g/kg/d) and rats in group A1B2 was not. Rats in groups A2B1 and A2B2 served as control groups, as well as rats in group A2B1 was given smectite powder(0.6g/kg/d) and those in group A2B2 was not. On the 4th day the rats were sacrificed and intestinal tissue were collected. On the 4th day all the subjects were sacrificed and intestinal tissues were obtained to examine. The intestine around ileocecal junction was for histological analysis and score. The remaining intestine was used to measure the content of PLA2 in homogenate of intestinal tissue. The histopatholigical changes were scored as 0(normal villi), 1(epithelial cell sloughing), 2(midvillous necrosis), 3(complete villous necrosis), or 4(transmural necrosis) in double-blind way. The mean score more than 2 were considered NEC. The contents of PLA2 in homogenate of intestinal tissue were measured by ELISA, and were expressed pg per mg protein of intestinal tissue. Kruskal-Wallis H test and factorial ANOVA were used to analyze difference among various groups.α=0.05 was considered significant.Result After separate from mother rats, feeding with rat milk substitute and induced by hypoxia and cold exposure several continual times, neonatal rats in groups A1B1 and A1B2 had diarrhea, abdominal distention, growth and development stepping down, activity reducing. As compared with group A1B2, there were remarkably relieved after given smectite powder in group A1B1. The scores of histological evaluation(?x±s ) in group A1B1, A1B2, A2B1 and A2B2 were .42±0.35,3.54±0.50,0.17±0.18 and 0.13±0.17, and the content of PLA2(?x±s, pg/mgprot ) in intestinal tissue were 1.1400±0.5349,1.7625±0.4993,0.4305±0.2054 and 0.5555±0.2476, respectively. The score of histopatholigical and the content of PLA2 in intestinal tissue had significant difference among groups. Comparing with that of group A1B2, the score of histopatholigical and the content of PLA2 in intestinal tissue of group A1B1 reduced, but that of group A1B1 was higher than two control groups significantly. By factorial ANOVA, two factors of model and smectite powder intervention had taken effect on the score of histopatholigical and the contents of PLA2 in intestinal tissue.Conclusion Smectite powder is beneficial to reduce the intestinal injury of neonate rats caused by formula feeding, hypoxia and cold exposure and decrease the incidence of NEC of neonate rats. It may decrease the endogenous production of PLA2 in intestinal tissue, which would be underlying protective mechanisms of smectite powder on NEC. |
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