腹泻状态下大鼠结肠水通道蛋白4表达的研究

目的检测腹泻后不同时间点大鼠升结肠和降结肠黏膜水通道蛋白4(AQP4)表达情况,探讨AQP4与结肠水转运的相关性。方法用反转录聚合酶链反应(RT-PCR)和免疫组织化学法分别对腹泻后3、9、15h时大鼠升、降结肠黏膜细胞AQP4 mRNA和AQP4蛋白表达进行定量分析。结果①正常对照组和腹泻组大鼠升、降结肠均有AQP4 mRNA和蛋白表达,且升结肠表达量明显高于降结肠(P<0.01);②腹泻各组升、降结肠AQP4 mRNA和蛋白表达量均较对照组减少(P<0.01),9h时减少最明显(P<0.01);③AQP4表达量随腹泻程度变化而变化,提示AQP4可能参与了结肠水代谢过程。结论腹泻状态下大鼠结肠黏膜AQP4表达下调,导致结肠对肠腔内水分的吸收减少,大便含水量增加形成腹泻,提示AQP4在结肠水代谢中具有重要意义。

Expression of aquaporin 4 in colonic epithelium of diarrheal rats

Objective To explore the expression of aquaporin (AQP4) in ascending and descending colonic mucosa of diarrheal rats, and to study the relationship between AQP4 expression and colonic water metabolism. Methods Hemi-quantitative RT-PCR and immunohistochemistry were used to detect the mRNA and protein expression of AQP4 in ascending and descending colonic mucosa of diarrheal rats at 3, 9 and 15 h from onset. Results AQP4 was expressed in ascending and descending colon of both normal and diarrheal rats, but much more in ascending than in descending colon (P<0.01). At all time spots, levels of AQP4 expression in ascending and descending colons of diarrheal rats were lower than in those of normal controls (P<0.05), particularly at 9h (P<0.01). AQP4 expression changed along with diarrhea severity, suggesting its role in colonic water metabolism. Conclusion AQP4 was down-regulated in colon of diarrheal rats. This may lead to decreased water reabsorption by the colon, hence more loose stool contributing to development of diarrhea, suggesting the role of AQP4 in colonic water metabolism.