Department of Molecular Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, P.O. Box 9063, Dublin 9, Ireland.
Steroids. 2011 Aug;76(9):867-76. doi: 10.1016/j.steroids.2011.04.016. Epub 2011 May 8.
Excessive Cl(-) secretion is the driving force for secretory diarrhea. 17β-Estradiol has been shown to inhibit Cl(-) secretion in rat distal colon through a nongenomic pathway. We examined whether 17β-estradiol inhibits Cl(-) secretion in an animal model of secretory diarrhea and the downstream effectors involved. The effect of 17β-estradiol on cholera toxin and heat-stable enterotoxin induced Cl(-) secretion in rat colonic mucosal sheets was studied by current-voltage clamping. Selective permeabilization of apical or basolateral membranes with amphotericin B or nystatin was used to isolate basolateral K(+) channel and apical Cl(-) channel activity, respectively. 17β-Estradiol dose-dependently inhibited secretory responses to both toxins with IC(50) values of approximately 1nM. This effect was female-gender specific, with no inhibition observed in male tissues. 17β-Estradiol responses were insensitive to the pure anti-estrogen ICI 182,720. 17β-Estradiol exerted its effects downstream of enterotoxin-induced production of second messengers (cAMP and cGMP) but was dependent on PKCδ activation. In nystatin-permeabilized tissues, apical Cl(-) currents were unaffected by 17β-estradiol treatment while basolateral K(+) current was profoundly inhibited by the hormone. This current was sensitive to the specific KCNQ1 channel inhibitors chromanol 293B and HMR-1556. In conclusion, 17β-estradiol inhibits enterotoxin-induced Cl(-) secretion via a PKCδ-dependent mechanism involving inhibition of basolateral KCNQ1 channels. These data elucidate mechanisms of 17β-estradiol inhibition of Cl(-) secretion induced by enterotoxins in intestinal epithelia, which may be relevant for the treatment of diarrheal diseases.
氯离子过度分泌是分泌性腹泻的驱动力。17β-雌二醇已被证明可通过非基因组途径抑制大鼠远端结肠的氯离子分泌。我们研究了 17β-雌二醇是否可抑制分泌性腹泻动物模型中的氯离子分泌及其涉及的下游效应物。通过电流电压钳研究了 17β-雌二醇对霍乱毒素和热稳定肠毒素诱导的大鼠结肠黏膜片氯离子分泌的影响。用两性霉素 B 或制霉菌素选择性通透顶膜或基底外侧膜，分别分离基底外侧钾通道和顶端氯离子通道活性。17β-雌二醇剂量依赖性地抑制两种毒素的分泌反应，IC50 值约为 1nM。这种作用具有雌性性别特异性，在雄性组织中观察不到抑制作用。17β-雌二醇反应对纯抗雌激素 ICI 182,720 不敏感。17β-雌二醇在肠毒素诱导的第二信使（cAMP 和 cGMP）产生的下游发挥作用，但依赖于 PKCδ 的激活。在制霉菌素通透的组织中，17β-雌二醇处理对顶端氯离子电流没有影响，而激素对基底外侧钾电流有强烈抑制作用。这种电流对特异性 KCNQ1 通道抑制剂 chromanol 293B 和 HMR-1556 敏感。总之，17β-雌二醇通过依赖于 PKCδ 的机制抑制氯离子分泌，该机制涉及抑制基底外侧 KCNQ1 通道。这些数据阐明了 17β-雌二醇抑制肠上皮细胞中肠毒素诱导的氯离子分泌的机制，这可能与腹泻病的治疗有关。
