| Objective To observe whether bifidobacterium's protection was related to the decrease of platelet-actvating factor (PAF) and the increase of secretory immunoglobulin A (SIgA) in intestinal tissue . In order to provide new Scientific basis and theoretical support for prevention and cure necrotizing enterocolitis (NEC).methods 84 neonate Sprague-dewley (SD) rats aged 2 days were divided into three groups at random,(no limit to male or female):Experimental group (A),control group (B) and Margin control group (C), n=28. A group were received bifidobacterium (each of 0.04g , contain 2.0 hundred million viable organism, treated by the PH 7.4 sodium chloride, 0.2ml per rat) with intragastric gavage , once per day, for one week. B group and C group were received the equal Sodium chloride solution, 0.2ml per rat, once per day, also one week. A week later, seven rats, selected form each group at random, were decapitated respectively at 2,6,12 and 24h after received injection of lipopolysaccharide (LPS) of A and B group. Obtained duodenum inferior to rectum superior intestinal tissue, in which the ileocecal junction was for histological analysis, and the remains was used to measure the content of PAF and SIgA with enzyme linked immunosorbent assay (ELISA) in homogenate of intestinal tissue. Software SPSS16.0 was used in all statistical tests and the measurement data were presented as mean( Xˉ)±standard deviation (SD).Comparisons between 3 groups were calculated using independent sample t test ,and the difference was considered to be significant if the P value was less than 0.05.Results1. The pathomorphology change of ileal tissue of each groupAfter LPS injected, the neonatal SD rats of B group appeared lazy,dispirited, 1-2h later showed diarrhea,abdominal distention, about 6h later this symptoms above were obvious, almost at the same time they appeard as tachypnea, cyanosis in lip, less activity, mess body hairs without gloss .The seriously sick showed spasm, cyanosis in four limbs, chilly body or even dead. Atfer killed those rats, we saw that their stomach accumulated very much, the wall of their intestines and mesentery congested, intestinal canal dilated and edema, exudation increased, seriously appeared spot-lamellar hemorrhage and necrosis. The symptoms mentioned above of survivor after 24h were partly relieved. Light microscopic examination after H-E staining: The intestinal epithelium and villi of B group denatured and atrophied 2h later. After 6h its intestinal epithelium structure disappeared completely, villi glandule shed and depleted, lamina propria's capillary congested and leukocyte infiltrated; about 12 hours later its structure began to repair but was unclear . Approximately 24h it was obviously clear! Compared with B group, A group appeared slight symptoms, and recovered quickly.2. The content of ileal tissue PAF and SIgA in different neonatal SD rats groupThe PAF activity of ileal tissue in B group were significantly increased at 2, 6 and 12h compared with C group ( P<0.05); and its content at A group were significantly decreased at 2, 6 and 12h compared with B group ( P<0.05);The SIgA activity of ileal tissue in A group were significantly increased at 2, 6 and 12h compared with C group ( P<0.05); and this in B group were significantly decreased at 2, 6 and 12h compared with A group ( P<0.05)Conclusions1. In neonatal SD rats of necrotizing enterocolitic model, by injecting LPS, the PAF content of ileal tissue were decreased obviously in treatment group, compared with B group. These showed that bifidobaterium maybe protect intestinal tissue by depressing the cascade reaction of inflammatory in which PAF was produced. And relieve the histopathological damage of ileum tissue in neonatal SD rats of necrotizing enterocolitic model .2. In neonatal SD rats of necrotizing enterocolitic model , by injecting LPS, the SIgA activity of ileal tissue were increased in treatment group rats, Compared with B group . These showed that bifidobaterium maybe protect intestinal tissue through secreting SIgA of intestine immunity.
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