5-HT/5-HT2B/BK信号通路对腹泻型肠易激综合征（IBS-D）的调控作用及机制研究

Diarrhea irritable bowel syndrome (IBS-D) is a disorder of intestinal function characterized by hyperkinetic disorder. Previous study showed that 5-HT in the serum and colon are increased of IBS-D patients. 5-HT could enhance intestinal motility. In our preliminary study, we found that after blocking BK channel, the ratio of 5-HT enhanced colonic motility decreased. Moreover, 5-HT could inhibited large conductance calcium-activated potassium channel (BK) mainly by binding to 5-HT2B receptor. However, whether 5-HT regulates intestinal motility through BK, and the signaling pathway and key molecules need to be further investigated. In this study, BK-/- mice and 5-HT2B mice will be used to establish IBS-D models. The motility of colonic smooth muscle was detected in vivo and in vitro, and the 5-HT/5-HT2B/BK signal axis was found to be involved in the regulation of IBS-D intestinal motility enhancement. To study the regulation of BK by downstream signaling pathway and the key signal molecules of 5-HT/5-HT2B, the BK channel currents are recorded using a patch clamp technique. The purpose of this study is to reveal the mechanism of gastrointestinal motility enhancement in IBS-D around the 5-HT/5-HT2B/BK signal axis, and to provide a new scheme for the accurate treatment of IBS-D.

腹泻型肠易激综合征（IBS-D）是以动力亢进为特点的肠道功能紊乱性疾病。有研究证实IBS-D患者血清以及结肠5-HT增高。5-HT可增强肠动力，我们预实验发现：阻断BK通道后，5-HT增强结肠动力能力下降；5-HT主要通过和5-HT2B受体结合抑制大电导钙激活钾通道（BK）。但5-HT是否通过BK调节肠道动力仍需证实，其调节BK的信号通路和关键分子尚不清楚。本课题拟用BK-/-鼠及5-HT2B-/-鼠制备IBS-D模型，在在体和离体水平检测结肠平滑肌动力，探明5-HT/5-HT2B/BK信号轴参与IBS-D肠动力增强的调节；利用膜片钳技术记录BK通道电流，研究5-HT/5-HT2B下游信号通路对BK的调节，寻找关键信号分子。本研究旨在围绕5-HT/5-HT2B/BK信号轴揭示IBS-D胃肠动力增强的机制，将为精准治疗IBS-D提供新方案。

本课题通过使用BK-/-鼠及5-HT2B-/-鼠制备腹泻型肠易激综合征（IBS-D）模型，使用western blot、PCR、免疫荧光、ELISA等实验技术手段阐明IBS-D结肠平滑肌5-HT/5-HT2B /BK 信号轴的表达类型及水平；在在体和离体水平检测结肠平滑肌动力，阻断BK通道后，5-HT增强结肠动力能力下降，5-HT主要通过和5-HT2B受体结合抑制大电导钙激活钾通道（BK），探明5-HT/5-HT2B/BK信号轴参与IBS-D肠动力增强的调节；通过利用膜片钳技术记录BK通道电流，明确5-HT/5-HT2B 及下游信号分子对BK 的调控机制及其在结肠平滑肌动力调节中的作用。本课题从离子通道的相关角度为IBS-D动力紊乱发病机制的探明和治疗策略的制定奠定基础，将为精准治疗IBS-D提供新方案。