Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, SA, Australia.
Discipline of Gastroenterology, College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, SA, Australia.
Commun Biol. 2021 Aug 10;4(1):955. doi: 10.1038/s42003-021-02485-4.
How the Enteric Nervous System (ENS) coordinates propulsion of content along the gastrointestinal (GI)-tract has been a major unresolved issue. We reveal a mechanism that explains how ENS activity underlies propulsion of content along the colon. We used a recently developed high-resolution video imaging approach with concurrent electrophysiological recordings from smooth muscle, during fluid propulsion. Recordings showed pulsatile firing of excitatory and inhibitory neuromuscular inputs not only in proximal colon, but also distal colon, long before the propagating contraction invades the distal region. During propulsion, wavelet analysis revealed increased coherence at ~2 Hz over large distances between the proximal and distal regions. Therefore, during propulsion, synchronous firing of descending inhibitory nerve pathways over long ranges aborally acts to suppress smooth muscle from contracting, counteracting the excitatory nerve pathways over this same region of colon. This delays muscle contraction downstream, ahead of the advancing contraction. The mechanism identified is more complex than expected and vastly different from fluid propulsion along other hollow smooth muscle organs; like lymphatic vessels, portal vein, or ureters, that evolved without intrinsic neurons.
肠神经系统(ENS)如何协调沿着胃肠道推进内容物一直是一个尚未解决的主要问题。我们揭示了一个解释 ENS 活动如何构成沿着结肠推进内容物的机制。我们使用了一种最近开发的高分辨率视频成像方法,同时记录平滑肌的电生理记录,在液体推进期间进行。记录显示,兴奋性和抑制性肌内传入的脉冲式放电不仅发生在近端结肠,而且也发生在远端结肠,远早于传播收缩侵入远端区域。在推进过程中,小波分析显示,在近端和远端之间的大距离上,2 Hz 左右的相干性增加。因此,在推进过程中,来自腹侧的下行抑制性神经通路的同步放电会抑制平滑肌收缩,抵消同一区域的兴奋性神经通路。这会导致下游肌肉收缩延迟,先于推进收缩。所确定的机制比预期的更复杂,与沿着其他中空平滑肌器官(如淋巴管、门静脉或输尿管)推进液体的机制有很大不同,这些器官在没有内在神经元的情况下进化而来。