本研究旨在探讨香菇多糖对大肠杆菌攻毒大鼠空肠形态结构、上皮细胞数量和紧密连接蛋白表达的影响。将24只SD大鼠随机分成4个组（A、B、C、D组），每组6个重复，每个重复1只。A、B组饮用蒸馏水，C、D组饮用蒸馏水中添加20 μg/mL的香菇多糖；试验第15天B、D组灌服2 mL浓度为1×10¹⁰ CFU/mL大肠杆菌K88，A、C组灌服等量生理盐水。试验第18天心脏采血处死，取空肠固定和冻存，制作石蜡切片，苏木精-伊红（HE）染色和高碘酸雪夫氏（PAS）染色，测定绒毛高度、隐窝深度、绒毛宽度、上皮内淋巴细胞（IEL）数量和上皮杯状细胞（GC）数量，计算绒毛高度与隐窝深度的比值（V/C）；并采用蛋白质印迹（Western-blot）法测定空肠紧密连接蛋白Occludin的表达水平。结果表明：各组绒毛高度和绒毛宽度无显著差异（P>0.05）。C组隐窝深度极显著低于A、B组（P<0.01），显著低于D组（P<0.05）。C组V/C极显著高于A、B、D组（P<0.01）。C组IEL数量极显著低于B、D组（P<0.01），显著低于A组（P<0.05）。C组上皮GC数量极显著高于A、D组（P<0.01），与B组差异不显著（P>0.05）。D组Occludin表达水平明显高于A、B和C组，B组Occludin表达水平高于A组。综上，大鼠饮用水中添加香菇多糖可改善大鼠空肠形态结构，并提高其抵抗大肠杆菌感染能力，促进Occludin的表达。

The study was conducted to investigate the lentinan on morphology structure, epithelial cell number and tight junction protein expression in jejunum of rats against Escherichia coli (E. coli). Twenty-four SD rats were randomly divided into 4 groups (groups A, B, C and D) with 6 replicates per group and 1 rat per replicate. Rats in groups A and B were drank distilled water and rats in groups C and D were drank distilled water supplemented with 20 μg/mL lentinan. In the 15^th days of experiment, rats in groups B and D were administered orally 2 mL E.coli K88 with the concentration of 1×10¹⁰ CFU/mL, meanwhile, rats in groups A and C were given the same amount of normal saline. In the 18th days of experiment, heart blood sampling, collected jejunum fixed and frozen, made paraffin sections and hematoxylin-eosin (HE) staining and periodic acid-schiff (PAS) staining. The villus height, crypt depth, villus width, number of intraepithelial lymphocytes (IEL) and epithelial goblet cells (GC) were measured and the ratio of villus height to crypt depth (V/C) was calculated. The expression of tight junction protein Occludin in jejunum was determined using Western-blot method. The results showed that no significant difference was observed in villus height and villus width among all groups (P>0.05). The crypt depth of group C was significantly lower than that of groups A and B (P<0.01), and significantly lower than that of group C (P<0.05). The V/C of C group was significantly higher than that of groups A, B and D (P<0.01). The IEL number of group C was significantly lower than that of groups B, D (P<0.01), and significantly lower than that of group A (P<0.05). The epithelial GC number of group C was significantly higher than that of groups A and D (P<0.01), and no significant difference compared with that of group B (P>0.05). The Occludin expression of group D was obvious higher than that of groups A, B and C, and the Occludin expression of group B was higher than that of group A. In conclusion, the drinking water of rats supplemented with lentinan can improve the jejunum morphology and enhance the ability of resisting E.coli and promote the expression of Occludin.