高蛋白膳食对限食大鼠肠免疫功能的保护作用

PROTECTIVE EFFECTS OF HIGH PROTEIN DIET ON INTESTINAL IMMUNE FUNCTION IN FOOD RESTRICTION RATS

目的探讨高蛋白膳食对限食大鼠肠免疫功能的保护作用,为高蛋白膳食防治限食引起的肠免疫功能损伤提供理论基础。方法 Wistar雄性大鼠,按体质量随机分成5组,分别为正常对照组(喂15%酪蛋白合成饲料并自由摄食)、限食1组和2组(分别按正常对照组摄食量的50%和30%对喂15%酪蛋白合成饲料);补蛋白1组和2组(分别按正常对照组摄食量的50%和30%对喂30%酪蛋白合成饲料)。实验2周后处死大鼠,取血和小肠组织检测小肠细菌移位率、血清内毒素及肠粘膜中SIgA水平。结果正常对照组未发生细菌移位,补蛋白1组的细菌移位率为25%,显著低于相应的限食1组(50%),差异有显著性(P<0.05)。补蛋白1组和2组的血清内毒素水平分别为(283.0±15.1)、(332.5±21.6)EU/L,均显著低于相应的限食组(341.2±29.1)、(434.2±24.3)EU/L,差异有显著性(P<0.05),但均显著高于正常对照组(16.3±3.0)EU/L,差异有显著性(P<0.01)。补蛋白1、2组肠粘膜SIgA水平均显著高于相应的限食组,差异有显著性(P<0.05),但均显著低于正常对照组,差异有显著性(P<0.05)。结论提高膳食中的蛋白质比例能增强肠道的免疫功能,减少细菌移位的发生,从而降低肠源性感染的机率。

Objective To study the protective role of high protein diet on intestinal immune function in food restriction rats,so as to provide the theoretical basis for prevention and treatment of damage to intestinal immune function. Methods Forty male Wistar rats were randomly divided into five groups： （1）normal control group （synthetic diet containing 15% casein, ad-libitum）;（2） food restriction group 1 （FR1 group, 15% casein, and 50% intake of normal control）;（3）supplementary protein group 1 （SP1 group, 30% casein, and 50% intake of normal control）; （4）food restriction group 2 （FR2 group, 15% casein, and 30% intake of normal control）;（5）supplementary protein group 2 （SP2 group, 30% casein, and 30% intake of normal control）. Two weeks later, blood and intestinal samples were collected to examine intestinal immune function. Results Normal control group did not have bacterial translocation in mesenteric lymph node,whereas in SP1 group, the number of translocation was significantly less than in FR1 group （2/8 vs 4/8, P〈0.05）. Serum endotoxin levels in SP1, SP2 group （283.0±15.1） EU/L, （332.5±21.6） EU/L respectively were singnificantly lower than in corresponding control FR1, FR2 group （341.2±29.1） EU/L, （434.2±24.3） EU/L respectively, （P〈0.05）, but higher than in normal control （16.3±3.0） EU/L,（P〈0.01）.Secretory IgA content in intestinal mucosa of protein supplemented groups was higher than in corresponding food restricted groups （P〈0.05）, but lower than in normal control（P0.05）. Conclusion Increasing protein proportion in foodstuff could enhance the intestinal immune function to reduce bacterial translocation, thus to decrease the chance of intestinal infection.