抗生素对新生大鼠肠道菌群和肠道免疫发育的影响

目的通过建立动物模型，探讨口服抗生素对新生大鼠肠道菌群的变化及肠道免疫发育的影响。方法选用30只7日龄新生SD大鼠，随机分为3组：抗生素组（A）、益生菌干预组（B）及对照组（C），每组10只，A组给予头孢克洛灌胃，B组先给头孢克洛灌胃，2h后再灌长双歧杆菌，C组每天灌以等量的生理盐水，持续2周后处死大鼠，留取盲肠内容物按照张秀荣方法进行肠道菌群检测，免疫组化方法进行肠组织CD4、CD8的测定。结果A组与B、C组相比，革兰阳性杆菌占肠道总细菌数比例明显下降，革兰阴性杆菌及革兰阳性球菌占总细菌数比例明显升高，差异均有显著性（P〈0．05）；A组肠组织中CD4、CD8表达程度受到抑制，与B、C组相比差异有显著性（P〈0．05），B、C两组所有的指标差异均无显著性。结论抗生素的应用会抑制肠道菌群的正常定植，引起菌群紊乱，进而影响肠道免疫系统发育。

Influences of antibiotics administration on the intestinal flora and immune system development of neonatal rats

Objective To investigate the impact of antibiotics administration on neenatal rat mode of intestinal flora and immunity system development. Method 30 neonate Sprague-Dewley rats （7 day olds, weighing 15 -21 g） were divided into 3 groups at random： antibiotic group （A）, probiotic intervention group （B） and control group （C）, 10 rats each group. The rats in Group A were given antibiotic （Cefaclor）. Group B were given Cefaclor first, then Bifidobacterium lungmn after 2 hours. Group C were given Sodium Chloride solution. All three groups were treated as above once per day for 2 weeks. On the fifteenth day, the rats were sacrificed. The intestinal flora in stools in Caecum of the rats were measured by ZHANG Xiu-rong method. The intestine around ileocecal junction was excised for the determination of indicators of immune system development by immunohistochemieal method. Result Compared with Group B and C, the proportion of G^＋ bacillus in the intestinal flora in group A decreased obviously, while that of G^- bacillus and G^＋ coccus in Group A increased obviously. There were a significant difference beween the groups （ P 〈 0.05）. The intestinal CD4 and CD8 expressions of Group A were inhibited, compared with Group B and C. There were a significant difference beween the groups （P 〈 0.05）. No significant difference beween Group B and C was observed. Conclusion Application of antibiotics will suppress the normal intestinal flora colonization, causing flora disturbance, thereby affecting the development of intestinal immune system.