双歧杆菌对新生大鼠坏死性小肠结肠炎肠损伤及肠道菌群影响

目的建立新生SD大鼠坏死性小肠结肠炎（NEC）模型，探讨添加双歧杆菌对新生大鼠NEC模型肠损伤的保护作用及肠道菌群的影响，为应用双歧杆菌防治NEC提供依据：方法SD新生大鼠出生48h开始给予鼠配方奶人工喂养，100％氮气缺氧90s，4℃冷刺激10min，每天2次，连续3d，建立新生SD大鼠NEC模型。按析因设计，32只新生SD大鼠随机分成4组，每组动物各8只。A组为NEC模型组并在出生48h起每日给予长双歧杆菌灌胃（1×10^8CFU／d）；B组为NEC模型组，C组为对照组，都未添加双歧杆菌；D组为对照组并给予长双歧杆菌灌胃（1×10^8CFU／d）。在最后一次缺氧、冷刺激后24h空腹断头处死大鼠，留取回盲部近端肠管组织进行肠组织损伤评分，组织学评分≥2确定为NEC；实验前后留取各组新生鼠粪便，按照张秀荣方法进行肠道菌群检测。应用Kruskal-Wallis H检验等方法进行统计学分析，α=0．05为显著性检验标准。结果开始造模后，A、B组新生SD大鼠相继出现腹泻、腹胀、萎靡、活动减少，A组程度较轻。A、B、C和D组肠组织损伤评分（^-x±s）分别为1．88±0.84、3．13±0．84、0．63±0．52、0．50±0.54，各组间肠组织损伤评分差异有显著性，与B组相比，A组肠组织损伤评分明显降低，但仍高于C、D两组，差异均有显著性。各组实验前肠道细菌总数，杆菌、球菌数，G^＋杆菌、G^＋球菌数差异均无显著性，肠道菌群中杆球菌比值在正常范围中。实验结束时，各组间新生鼠肠道细菌总数，杆菌、球菌数，杆球菌比值，G^＋杆菌、G^＋球菌数及其占肠道总菌群数的比率差异均有显著性；除B组杆菌数外，与实验前相比，各组新生大鼠实验结束后肠道细菌总数、球菌数、杆菌数、G^＋杆菌数、G^＋球菌数均有显著增加，差异均有显著性；A、B组肠道杆球菌比值和G^＋杆菌数占肠道总菌群数比

Effects of Bifidobacterium longum on neonatal rat model of necrotizing enterocolitis and roles of intestinal flora

Objective To investigate the effect of Bificobacterium longum on the scores of histological evaluation and the change of intestinal flora in neonatal SD rat model of necrotizing enterocolitis （NEC）. Methods According to 2 × 2 factor analysis,32 neonate Sprague-Dewley rats（48 h olds,weighing 5 ～10 g） were divided into 4 groups. Rats in Group A and B were made into NEC models,C and D were served as control groups. Rats in group A and were given Bifidobacterium Iongum（10^8CFU/d） and rats in group B and C wcre not. The intestine around ileocecal junction was for histological analysis and score. The mean score more than 2 were considered NEC. The intestinal flora in stools of neonatal rats were measured by ZHANG Xiu-rong method. Results At the end of the expartment,neonatal rats in Groups A and B had diarrhea,abdominal distention,intestinal hemorrhage,pneumatosis and necrosis of intestine in some degree were found. As compared with group B ,the manifestations of group A were remarkably relieved after given Bificobacterium longum. The scores of histological evaluation （ ^-x± s） in group A, B, C and D were 1.88 ± 0. 84,3.13 ±0. 84, 0. 63 ±0. 52 and 0. 50±0. 54, respectively. The score of histopatholigieal had significant difference among groups, H = 22. 626, P 〈 0. 01. Comparing with that of group B,the score of histopatholigieal of group A reduced,but that of group A was higher than two control groups significantly. Incidences of NEC in Group A and B were 37.5% （3/8）,100% （8/8）. In Group A,B,C and D,the amount of total intestinal baeteri-al,total bacillus and coccus, G^＋ bacillus,G^＋ coccus in the intestinal flora were no different before the experiment ,but were increased significantly compared with that of before experiment in group A,C and D. The ratio of bacillus to coccus and the proportion of G^＋ bacillus in the intestinal flora in group A and B decreased obviously,but group A decreased less than that of group B,and the G^＋ coccus accounting for intestinal flora in group