大黄蒽醌衍生物对大鼠结肠及LoVo细胞水通道蛋白4表达的调节效应

Regulatory Effect of Anthraquinone Derivatives from Rhubarb on Aquaporin 4 Expression in Colon of Rats and in LoVo Cell Line

目的探讨大黄总蒽醌对SD大鼠的泻下效应及对结肠水通道蛋白4(aquaporin4,AQP4)表达的影响及大黄酸、大黄素对体外培养LoVo细胞AQP4的调节效应。方法雄性SD大鼠24只随机分为正常对照组、大黄总蒽醌泻下剂量组及高剂量组,分别予大黄总蒽醌悬液或蒸馏水灌胃5天,观察大鼠结肠粪便含水量;应用Western blot、RT-PCR方法观察其近端结肠AQP4表达的变化。体外培养LoVo细胞并予不同浓度大黄酸/大黄素含药培养液作用24 h及大黄酸/大黄素含药培养液(20 mg/L)不同时间作用,采用Western blot及RT-PCR检测AQP4蛋白及mRNA的表达。结果大黄总蒽醌泻下剂量组及高剂量组作用后,大鼠结肠内粪便含水量明显增加,同时其近端结肠AQP4表达降低且表现为量效关系。大黄酸/大黄素能够显著下调体外培养LoVo细胞的AQP4蛋白及mRNA表达,且表现为剂量-效应及时间-效应关系。结论大黄总蒽醌在发挥泻下作用的同时,能够有效下调大鼠近端结肠AQP4的表达;大黄酸、大黄素可抑制体外培养Lo- Vo细胞AQP4的表达,可能是大黄泻下作用机制之一。

Objective To investigate the cathartic effect of total anthraquinone （AQ） from rhubarb on SD rats and its regulatory effect on aquaporin 4 （AQP4） expression in rat colon and in vitro cultured LoVo cell line. Methods Twenty-four SD rats were randomly divided into the normal control group treated with distilled water, and the two AQ groups administered with AQ suspension in cathartic and high dose （AQcd and AQhd） respectively via gastrogavage for 5 days. Water content in colonic stool was detected and the expression of AQP4 in rat＇s proximal colon was measured using Western blot and RT-PCR. LoVo cells cultured in vitro were used in the experimental study. The AQP4 protein and mRNA expressions in the cells were detected by Western blot and semiquantitative RT-PCR after they were cultured for 24 h with RPMI-1640 medium containing rhein/emodin in different concentra- tions, and those cultured with RPMI-1640 containing 20 mg/L rhein/emodin for different time points. Results After treatment, the stool water content in the AQcd and AQhd groups was higher than that in the control group and the AQP4 expression in rats treated with AQ decreased in a dose-dependent manner. The study showed that rhein/emodin could significantly down-regulate the protein and mRNA expressions of AQP4 in cultured LoVo cells, with the effectiveness related with dose and acting time. Conclusion At the same time of playing cathartic action, total AQ of rhubarb can effectively down-regulate the expression of AQP4 in rat＇s proximal colon; rhein/emodin can suppress the AQP4 expression in LoVo cells in vitro. One mechanism of cathartic effect of rhubarb AQ is possibly its down-regulation on AQP4 expression.