本文为探索益生菌对生长发育和免疫功能的影响及作用机理，给正常幼鼠灌胃低、中、高剂量益生菌后，检测各实验动物生长发育和免疫功能相关指标。结果显示与对照组比较，不同剂量益生菌使幼鼠的体重平均增重率分别增加7.56%、14.45%和1.32%；采食量平均增加0.31%、0.90%和0.13%，料重比平均降低3.89%、3.74%和4.47%；中剂量组和高剂量组股骨长度分别增加1.17%和1.69%；α-淀粉酶活力增加率分别为1.48%、1.28%和1.0%；免疫器官胸腺和肝脏器指数分别增加23.65%、24.68%、25.45%和0.34%、6.99%、0.70%；中剂量组和高剂量组血清中IL-6表达量分别增加5.40%和23.15%；T淋巴细胞转化率和B淋巴细胞转化率分别增加4.55%、6.50%、12.11%和7.90%、9.64%、13.71%；结肠上皮紧密连接蛋白Claudin1表达均增强，且随着给药剂量增加而增强。说明益生菌主要通过增强肠道消化酶活力，增加对营养物质吸收，促进体重和股骨生长；同时通过增加免疫因子IL-6表达，提高T淋巴细胞和B淋巴细胞活力，增强结肠上皮紧密连接蛋白Claudin1的表达，促进免疫脏器胸腺和肝的发育与成熟来提高机体免疫功能。

To explore the effects and mechanism of probiotics on growth, development, and immune function, normal young rats were given low, medium, and high doses of probiotics by gavage for 28 days, and then related indicators of growth, development, and immune function were measured. The results showed that, compared with the negative control group, different doses of probiotics had a growth-promoting effect. The rates of weight gain were increased by 7.56% (low-dose group), 14.45% (medium-dose group), and 1.32% (high-dose group), and food intake was increased by 0.31% (low-dose group), 0.90% (medium-dose group), and 0.13% (high-dose group). Feed-weight ratios were decreased by 3.89% (low-dose group), 3.74% (medium-dose group), and 4.47% (high-dose group). Femur lengths were increased by 1.17% (medium-dose group) and 1.69% (high-dose group), and the activity of α-amylase in the jejunum was increased by 1.48% (low-dose group), 1.28% (medium-dose group), and 1.0% (high-dose group). Thymus indices were increased by 23.65% (low-dose group), 24.68% (medium-dose group), and 25.45% (high-dose group), and liver indices were increased by 0.34% (low-dose group), 6.99% (medium-dose group), and 0.70% (high-dose group). The expression of interleukin-6 (IL-6) in the serum was increased by 5.40% (medium-dose group) and 23.15% (high-dose group). T-lymphocyte transformation rates were increased by 4.55% (low-dose group), 6.50% (medium-dose group), and 12.11% (high-dose group); B lymphocyte transformation rates were increased by 7.90% (low-dose group), 9.64% (medium-dose group), and 13.71% (high-dose group). The expression of tight-junction protein claudin-1 in colonic epithelium was enhanced, and showed a positive correlation with doses. The results indicated that probiotics could increase body weight and femur length by enhancing the activities of intestinal digestive enzymes and promoting the absorption of nutrients. Probiotics could also enhance the expression of IL-6, improve the activities of T-cells and B-cells, and strengthen the expression of tight-junction protein claudin-1 to promote the development and maturation of immune system organs (thymus and liver) and improve immunity.

国家自然科学基金项目（81473540、81473319）；广东省科技计划项目（2014A020221027、2013B090800011、2014B040404010、2015A030401031）