The enteric nervous system controls much of the mixing and propulsion of nutrients along the digestive tract. Enteric neural circuits involve intrinsic sensory neurons, interneurons and motor neurons. While the role of the excitatory motor neurons is well established, the role of the enteric inhibitory motor neurons (IMNs) is less clear. The discovery of inhibitory transmission in the intestine in the 1960 in the laboratory of Geoff Burnstock triggered the search for the unknown neurotransmitter. It has since emerged that most neurons including the IMNs contain and may utilise more than one transmitter substances; for IMNs these include ATP, the neuropeptide VIP/PACAP and nitric oxide. This review distinguishes the enteric neural pathways underlying the ‘standing reflexes’ from the pathways operating physiologically during propulsive and non-propulsive movements. Morphological evidence in small laboratory animals indicates that the IMNs are located in the myenteric plexus and project aborally to the circular muscle, where they act by relaxing the muscle. There is ongoing ‘tonic ‘activity of these IMNs to keep the intestinal muscle relaxed. Accommodatory responses to content further activate enteric pathways that involve the IMNs as final neural element. IMNs are activated by mechanical and chemical stimulation induced by luminal contents, which activate intrinsic sensory enteric neurons and the polarised interneuronal ascending excitatory and descending inhibitory reflex pathways. The latter relaxes the muscle ahead of the advancing bolus, thus facilitating propulsion.

肠道神经系统控制着大部分营养物质沿消化道的混合和推进。肠神经回路涉及内在感觉神经元、中间神经元和运动神经元。虽然兴奋性运动神经元的作用已经确立，但肠抑制性运动神经元 (IMN) 的作用尚不清楚。1960 年在 Geoff Burnstock 实验室发现的肠道抑制性传递引发了对未知神经递质的探索。后来发现，包括 IMN 在内的大多数神经元都含有并可能利用一种以上的递质物质；对于 IMN，这些包括 ATP、神经肽 VIP/PACAP 和一氧化氮。这篇综述将“站立反射”背后的肠道神经通路与推进和非推进运动期间生理上运行的通路区分开来。小型实验动物的形态学证据表明，IMN 位于肌间神经丛中，并从外侧投射到环形肌肉，在那里它们通过放松肌肉来发挥作用。这些 IMN 正在进行“强直”活动，以保持肠道肌肉放松。对内容的适应性反应进一步激活涉及 IMN 作为最终神经元件的肠道通路。IMN 由管腔内容物诱导的机械和化学刺激激活，其激活内在感觉肠神经元和极化的神经元间上行兴奋性和下行抑制性反射通路。