疏肝健脾方对腹泻型肠易激综合征模型大鼠结肠黏膜多巴胺信号通路离子转运的影响

Effect of Shugan-Jianpi prescription (SJP)on the ion transport of colon mucosa in IBS-D rats induced by dopamine

[目的]通过观察疏肝健脾方对腹泻型肠易激综合征(IBS-D)模型大鼠多巴胺信号通路结肠黏膜离子转运的影响,旨在探讨疏肝健脾方对IBS-D的疗效机制。[方法]将体质量180～220g雄性SD大鼠随机分为正常对照组、IBS-D模型组和疏肝健脾方治疗组,除正常对照组外,其他2组进行造模;采用体外短路电流测量技术测定各组大鼠结肠黏膜的短路电流变化。[结果]3组大鼠在基础电流、基础电压及跨上皮电阻三项电参数方面比较均差异无统计学意义(P>0.05);多巴胺(DA)引起的最大短路电流下降值(△Isc),疏肝健脾方治疗组较IBS-D模型组明显减小(P<0.05);将Cl-,HCO3-,Cl-/HCO3-从K-HS液中替代后,3组大鼠的△Isc均减小但3组间△Isc比较差异无统计学意义(P>0.05);分别采用非选择性Cl-通道阻断剂glibenclamide、DPC阻断顶膜侧Cl-转运后,3组大鼠的△Isc均减小但3组间△Isc比较差异无统计学意义(P>0.05);采用上皮Na+通道阻断剂Amiloride阻断顶膜侧的Na+转运后、非选择性K+通道阻断剂Ba2+阻断顶膜侧K+转运后,3组大鼠的△Isc均基本不受影响,疏肝健脾方治疗组较IBS-D模型组明显减小(P<0.05);采用抑制剂Bumitanide抑制黏膜基底侧Na+-K+-2Cl-共转运体的离子、抑制剂SITS抑制黏膜基底侧Cl-/HCO3-转运后,3组大鼠的△Isc均减小但3组间△Isc比较差异无统计学意义(P>0.05)。[结论]疏肝健脾方对IBS-D模型大鼠治疗作用的发挥与其对大鼠结肠黏膜多巴胺通路相关的Cl-及HCO3-转运的调节作用有关,这一过程主要由结肠黏膜顶膜侧Cl-通道,基底膜侧阴离子交换体及Na+-K+-2Cl-共转运体等膜通道蛋白共同介导。

[Objective]To investigate the mechanism of Shugan-Jianpi prescription（SJP）on the ion transportation of diarrhea predominant irritable bowel syndrome（IBS-D）colon mucosa induced by dopamine（DA）.[Methods]Male Sprague-Dawley rats（180-220 g）were randomly divided into three groups：normal group,IBS-D group and SJP group.IBS-D rat model was induced by intracolonic instillation of acetic acid and restraint stress.The SJP group was intragastrically administered with SJP,the normal group and IBS-D group were given equivalent volume of 0.9% NaCl.The short circuit current（Isc）technique was employed for the colon segments test in vitro with bathing instrument.The influence of SJP and specific ion channel inhibitor on the Isc of colon mucosa induced by DA was then observed.[Results]The rat distal colon of IBS-D,normal and SJP group showed no difference in potential difference（PD）,basal current（BC）and transepithelial resistance（TR）（P〉0.05）;Compared to the IBS-D group,the short circuit current change（△Isc）of SJP group induced by DA significantly decreased（P〈0.05）,howerer,when Cl-,HCO3-or Cl-/HCO3-were substituted from the Kreb-Henseleit solution（K-H S）,this difference disappeared（P〉0.05）and the △Isc of three groups decreased;When non-selective Cl-channel blocker DPC（1 mmol/L）or glibenclamide（1 mmol/L）was added into apical side,the △Isc of three groups decreased and there was no significant difference between SJP group and IBS-D group（P〉0.05）;The △Isc of SJP group decreased than IBS-D group when apically added with amiloride（100μmol/L）,an epithelial Na＋ channel blocker（P〉0.05）;When apically added with putative K＋ channel blocker BaCl2（5 mmol/L）,the △Isc of SJP group significantly decreased than the IBS-D group（P〈0.05）;when basolaterally added with Cl-/HCO3-exchanger inhibitor SITS（100μmol/L）or Na＋-K＋-2Cl-cotransportor（NKCC）inhibitor bumetanide（100μmol/L）,the △Isc induced by DA between SJP group and IBS-D group showed no difference（P〉0.05）.[Conclusion]SJP may treat IBS-D rat through regulating the DA related transepithelial transportation of Cl-and HCO3-.The coordination of apical Cl-channel,basolateral NKCC,Cl-/HCO3-cotransportor may be involved in this procedure.