小鼠低菌模型的构建及多形拟杆菌对其补偿生长作用的研究

A study of establishing low-level bacterium model and the effects of Bacteroides thetaiotaomicron on compensated growth in model mice

目的探讨高剂量抗生素构建低菌小鼠模型的可行性，并研究小鼠在不同生理状态下肠内拟杆菌的演替规律及对小鼠生长性能的影响。方法将120只SPF级的昆明小鼠分成3组：A组为空白对照组；B组为模型组，用22g/（kg·BW）的氨苄青霉素连续灌胃小鼠3d构建低菌动物模型；C组在构建低菌小鼠模型的基础上每天早晚2次各灌胃1ml的多形拟杆菌发酵液（10^9／m1），连续3d。用注射器稀释法测定小鼠肠内拟杆菌的活菌数，并测定各组小鼠体重和日增重。结果高剂量的抗生素处理可以使小鼠保持16d的低菌状态，但是给小鼠带来了一定的应激；C组小鼠在灌胃多形拟杆菌发酵液后，肠内拟杆菌在22～34d迅速生长并形成优势定植，且体重和日增重在实验后期显著增加即补偿生长。结论低菌模型较常规动物更能敏感地反映添加拟杆菌的生物学效应，但对小鼠有一定应激；多形拟杆菌对低菌小鼠具有明显的补偿生长效应，它可以缓解应激并使小鼠更快的恢复到正常的生理状态。

Objective To investigate the feasibility of low-level bacterium model by administering high-dose antibiotics ampicillin,the Bacteriodes succession in three different physiological condition and the effects of B. thetaiotaomicron on compensated growth in model mice. Methods One hundred and twenty 20-day-old Kunming mice were randomly allocated into three groups, and each group contained 40 mice. A was control group. B was low-level bacterium model group, in which each mouse was intragastriced infusion ampicillin 0.5 g continuously for three days in order to establish low-level bacterium mice model. In group C ,first we established the low-level bacterium model and then the 40 mice-model were administered with 1 ml B. thetaiotaomicron liquid fermentation（10^9/ml） by gastric infusion twice a day for 3 days. Results The group B could establish a low-level bacterium environment, and it could keep this situation for 16 days which caused side-effect on the model-mice. Compared to group A,in the end of the experiment （from 28 d to 34 d） daily gain had a rapidly increase in group C,this was called as compensated growth. Conclusions The low-level bacterium model-mice could open sensitively out the biological function of B. thetaiotaomicron, but had a stress, the administering B. thetaiotaomicron had the effects of compensated growth in model mice. It could moderate the stress and make mice recover the normal physiological condition as soon as possible.