Activity in varicosities within the myenteric plexus between and during the colonic migrating motor complex in the isolated murine large intestine
Activity in varicosities within the myenteric plexus between and during the colonic migrating motor complex in the isolated murine large intestine
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DOI：
10.1111/j.1365-2982.2012.01892.x
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发表时间：
2012-04-01
影响因子：
3.5
通讯作者：
Smith, T. K.
中科院分区：
文献类型：
--
作者：
Bayguinov, P. O.;Broadhead, M. J.;Smith, T. K.
背景 当沿神经纤维的动作电位在静脉曲张中产生 Ca2+ 瞬变，导致囊泡胞吐作用和神经递质释放时，肌间丛内的神经元通讯就会发生。我们使用静脉曲张中的 Ca2+ 瞬变来监测离体小鼠结肠中结肠迁移运动复合体 (CMMC) 之间和期间肌间神经通路的动作电位活动。方法 去除纵向肌肉条，露出肌间神经节，然后加载 Fluo-4。主要结果 许多静脉曲张，包括突触结合蛋白 1 标记的静脉曲张，表现出持续的 Ca2+ 瞬变（单一 Ca2+ 瞬变的持续时间为 3.9 秒）。在 CMMC 之间，静脉曲张以 0.6 Hz 的频率发射，这与环肌中的自发抑制连接电位相关，表明它们主要位于抑制神经通路中。在 CMMC 期间，其他先前静止的静脉曲张在 CMMC 持续时间（24 秒）内以 1.3 Hz（最大 2.0 Hz）发射，表明它们处于兴奋性神经通路上。静脉曲张的活动与许多神经元中的 Ca2+ 瞬时反应相关。一些静脉曲张似乎会释放一种抑制性神经递质，减少 nNOS 阳性神经元的活动。沿着同一神经纤维的静脉曲张表现出相同的活动模式，使得可以在整个肌间神经丛和结间束中追踪神经纤维。六甲铵 (100 lmol L) 1) 可降低静脉曲张的活性，并可被 x-芋螺毒素 GVIA (200 nM) 和河豚毒素 (1 lmol L) 1 阻断；文本）。结论与推论 静脉曲张的 Ca2+ 成像可以确定肠神经系统内神经通路的活动。
Background Neuronal communication within the myenteric plexus occurs when action potentials along nerve fibers produce Ca2+ transients in varicosities leading to exocytosis of vesicles and neurotransmitters release. We used Ca2+ transients in varicosities to monitor action potential activity in myenteric nerve pathways both between and during the colonic migrating motor complex (CMMC) in the isolated murine colon. Methods Strips of longitudinal muscle were removed to reveal the myenteric ganglia, which were then loaded with Fluo-4. Key Results Many varicosities, including synaptotagmin 1 labeled varicosities, exhibited ongoing Ca2+ transients (duration of unitary Ca2+ transient 3.9 s). Between CMMCs, varicosities fired at a frequency of 0.6 Hz, which correlated with spontaneous inhibitory junction potentials in the circular muscle, suggesting they were mainly in inhibitory nerve pathways. During a CMMC other previously quiescent varicosities fired at 1.3 Hz (max. 2.0 Hz) for the duration (24 s) of the CMMC, suggesting they were on excitatory nerve pathways. Activity in varicosities was correlated with Ca2+ transient responses in a number of neurons. Some varicosities appeared to release an inhibitory neurotransmitter that reduced activity in nNOS-positive neurons. Varicosities along the same nerve fiber exhibited identical patterns of activity that allowed nerve fibers to be traced throughout the myenteric plexus and internodal strands. Activity in varicosities was reduced by hexamethonium (100 lmol L) 1), and blocked by x-conotoxin GVIA (200 nM) and tetrodotoxin (1 lmol L) 1; TTX). Conclusions & Inferences Ca2+ imaging of varicosities allows for a determination of activity in neural pathways within the enteric nervous system.