肠神经系统与离子通道重塑对结肠炎结肠动力的调节

Colonic dysmotility is a common complication of colitis, and the velocity of propulsive motility is slowed or halted in the inflamed regions. However, the mechanisms of inflammation-induced dysmotility are largely unknown. The enteric nervous system（ENS） and ion channels located in smooth muscle cells play important roles in regulating intestinal motility. Myenteric neurons such as cystathionine-γ-lyase（CSE) neurons and neuronal nitric oxide synthase（nNOS） neurons are the important inhibitory motor neurons. In the gastrointestinal tract, the physiological role of voltage-dependent potassium channels (KV), large conductance Ca2+-activated potassium channels (BKca), and ATP-sensitive potassium channels (KATP) may be related to the modulation of the excitability of smooth muscle cells. Little is known about the link between the plasticity of the aforementioned enteric neurons and ion channels and intestinal dysmotility in colitis. This project intends to explore the plasticity of two colonic myenteric neurons (nNOS and CSE) and three ion channels（KV, BKca, and KATP）in a rat model of 2、4、6-trinitrobenzenesulfonic-acid-inflamed colonic dysmotility, using a series of methods such as electrophysiology and cell and molecular biology technologies, from multiple levels such as whole body, tissues, cells, and ion channels. We will also examine the role of inhibitors of nNOS and CSE in regulating colonic dysmotility and the interaction between H2S /CSE and NO/nNOS. This will provide a theoretical basis for the prevention and treatment of inflammation-induced colonic dysmotility.

结肠动力紊乱是结肠炎常见临床表现，病变部位蠕动减慢或消失、粪便推进率下降，其动力紊乱发生机制尚未完全明确。肠神经系统及离子通道对动力调节有重要作用。肌间胱硫醚-γ-裂解酶(CSE)神经元及神经型一氧化氮合成酶(nNOS)神经元是重要的抑制性运动神经元，电压依赖性钾通道（KV)、大电导钙依赖钾通道（BKca)、ATP敏感性钾通道(KATP)调控胃肠道平滑肌舒缩，目前未见以上神经元及离子通道重塑与结肠炎动力相关研究。本项目拟采用2、4、6-三硝基苯磺酸灌肠构建结肠炎大鼠模型，采用电生理学、免疫组化、细胞与分子生物学等方法，从整体、组织、细胞、分子、离子通道等多个层面探讨CSE 、nNOS神经元及KV、BKca、KATP重塑对结肠炎结肠动力影响；同时通过抑制实验进一步探讨肠神经元抑制剂对结肠炎动力紊乱的调节及H2S /CSE与NO/nNOS体系的相互影响，为结肠炎结肠动力紊乱防治提供理论基础。

肠道动力紊乱是结肠炎常见并发症，H2S对结肠动力紊乱及结肠炎症的作用尚未完全阐明。本项目构建结肠炎大鼠模型，探讨外源性H2S是否通过调节钙离子通道重塑介导大鼠结肠炎的结肠动力紊乱的发生以及H2S是否通过抑制NLRP3和激活自噬来改善结肠炎症反应。结果显示：结肠炎组大鼠体重明显下降、排便数量明显减少、碳粉在结肠中的移动距离明显缩短，结肠炎大鼠结肠黏膜组织损伤，IL-1β、IL-6、TNF-α3种炎性介质水平均显著升高、钙离子分布比对照组更集中、KCND3基因、KCNMA1基因和KCNJ8基因表达下调，H2S干预后对结肠炎大鼠体重、大便粒数、结肠炎症、IL-1β、IL-6、TNF-α3种炎性介质水平，钙离子分布有明显改善，三种基因mRNA和蛋白表达明显升高； NaHS可减轻结肠炎诱导的组织学损伤和炎症反应，NaHS可导致结肠炎大鼠结肠CSE和H2S的下调，NaHS处理后结肠炎大鼠LC3B上调，NaHS在体外降低了活氧簇水平，NaHS降低了LPS刺激细胞的CSE和NLRP3水平，NaHS通过调节自噬蛋白水平证实了自噬的增强。结论： H2S可改善肠道黏膜状况及全身炎症情况，通过来重建离子通道改善结肠炎肠道动力紊乱。H2S可通过抑制NLRP3和激活自噬来改善结肠炎症反应，H2S对结肠炎具有潜在的治疗作用。