慢性酒精刺激对结肠壁大肠杆菌脂多糖通透的影响

Changes of mucosal permeability to lipopolysaccharide in the colon of chronic alcoholic rats

目的探讨慢性酒精刺激对结肠壁粘膜大肠杆菌脂多糖通透的影响．方法Ｌｉｅｂｅｒ酒精饮食喂养６周之实验大鼠（ｎ＝１０），于横结肠肠腔内注入大肠杆菌脂多糖（２０μｇ／ｍｌ）．注射脂多糖前及注射后５，１０，２０，３０ｍｉｎ自同一动物分别取门静脉血０５ｍｌ测定脂多糖含量．取该段结肠固定，应用单克隆抗脂多糖抗体及异硫氰酸荧光素标记二抗进行免疫荧光染色，激光共聚焦扫描显微镜下观察抗脂多糖荧光分布．正常大鼠为对照（ｎ＝６）．结果慢性酒精刺激大鼠结肠腔内注射脂多糖前其门静脉血液中脂多糖含量显著高于正常对照大鼠（３５６ｎｇ／Ｌ±０６７ｎｇ／Ｌｖｓ２４５ｎｇ／Ｌ±０１５ｎｇ／Ｌ，Ｐ＜００１），注射脂多糖后不同时间点其门静脉血脂多糖含量均显著高于注射前水平（１７３５６ｎｇ／Ｌ±２３４５ｎｇ／Ｌ，１５４７８ｎｇ／Ｌ±２０５７ｎｇ／Ｌ，４３８９ｎｇ／Ｌ±８６７ｎｇ／Ｌ，４５３８ｎｇ／Ｌ±７８９ｎｇ／Ｌｖｓ３５６ｎｇ／Ｌ±０６７ｎｇ／Ｌ，Ｐ＜００１），且其结肠段粘膜层绝大多数细胞胞浆内呈强烈抗脂多糖荧光显色．正常对照大鼠注射脂多糖后门静脉血液中脂多糖含量无明显升高（Ｐ＞００５），结肠段粘膜细胞内未见明显?

AIM To evaluate the effects of chronic alcohol abuse on the mucosal permeability to lipopolysaccharide in the colon of rats. METHODS Escherichia coli lipopolysaccharide (LPS, 20μg/ml) was injected into the colon of chronic alcoholic rats ( n =10) which were supplied with Lieber diets every other day for 6 weeks. Before LPS injection and 5, 10, 20, 30 minutes after the injection, blood samples from the portal vein were obtained and contents of LPS in the blood were measured. The distribution of LPS in the colon tissues was observed with a confocal laser scanning microscope by immunofluorescent technique using the monoclonal antibody specific to the lipid A region of LPS. Normal rats were used as controls ( n =6). RESULTS Before LPS injection in the colon, LPS levels in the blood of portal vein of chronic alcoholic rats were significantly higher than those of normal controls (3 56ng/L±0 67ng/L, vs 2 45ng/L±0 15ng/L, P <0 01). At 5, 10, 20, 30 minutes after the injection of LPS, LPS contents were significantly higher than those before LPS injection (173 56ng/L±3 45ng/L, 154 78ng/L±0 57ng/L, 43 89ng/L±0 67ng/L, 45 38ng/L±0 89ng/L vs 3 56ng/L±0 67ng/L, P <0 01, respectively). Most mucosal cells showed strong positive reactions to LPS in the rats of chronic alcohol abuse, but no significant changes of LPS contents in blood from the portal vein and fluorescent reactions to LPS in mucosal cells of normal rats were found after LPS injection. CONCLUSION Chronic alcohol abuse resulted in a significant increase of permeability to LPS in colon mucosal cells in rats.