Buckley Maria M, O'Malley Dervla
Department of Physiology, University College Cork, Cork, Ireland.
APC Microbiome Institute, University College Cork, Cork, Ireland.
Front Neurosci. 2018 Feb 27;12:112. doi: 10.3389/fnins.2018.00112. eCollection 2018.
Bidirectional signaling between the gastrointestinal tract and the brain is vital for maintaining whole-body homeostasis. Moreover, emerging evidence implicates vagal afferent signaling in the modulation of host physiology by microbes, which are most abundant in the colon. This study aims to optimize and advance dissection and recording techniques to facilitate real-time recordings of afferent neural signals originating in the distal colon. This paper describes a dissection technique, which facilitates extracellular electrophysiological recordings from visceral pelvic, spinal and vagal afferent neurons in response to stimulation of the distal colon. Focal application of 75 mM KCl to a section of distal colon with exposed submucosal or myenteric nerve cell bodies and sensory nerve endings evoked activity in the superior mesenteric plexus and the vagal nerve. Noradrenaline stimulated nerve activity in the superior mesenteric plexus, whereas application of carbachol stimulated vagal nerve activity. Exposure of an section of distal colon with an intact colonic mucosa to peptidoglycan, but not lipopolysaccharide, evoked vagal nerve firing. Previous studies have recorded vagal signaling evoked by bacteria in the small intestine. The technical advances of this dissection and recording technique facilitates recording of afferent nerve signals evoked in extrinsic sensory pathways by neuromodulatory reagents applied to the distal colon. Moreover, we have demonstrated vagal afferent activation evoked by bacterial products applied to the distal colonic mucosa. This protocol may contribute to our understanding of functional bowel disorders where gut-brain communication is dysfunctional, and facilitate real-time interrogation of microbiota-gut-brain signaling.
胃肠道与大脑之间的双向信号传导对于维持全身稳态至关重要。此外，新出现的证据表明迷走神经传入信号参与微生物对宿主生理的调节，而微生物在结肠中最为丰富。本研究旨在优化和改进解剖与记录技术，以促进对源自结肠远端的传入神经信号进行实时记录。本文描述了一种解剖技术，该技术有助于对内脏盆腔、脊髓和迷走神经传入神经元进行细胞外电生理记录，以响应结肠远端的刺激。将75 mM氯化钾局部应用于一段暴露有黏膜下或肌间神经细胞体以及感觉神经末梢的结肠远端，可诱发肠系膜上丛和迷走神经的活动。去甲肾上腺素刺激肠系膜上丛的神经活动，而应用卡巴胆碱则刺激迷走神经活动。将一段具有完整结肠黏膜的结肠远端暴露于肽聚糖而非脂多糖中，可诱发迷走神经放电。先前的研究已经记录了小肠中细菌诱发的迷走神经信号传导。这种解剖和记录技术的技术进步有助于记录通过应用于结肠远端的神经调节试剂在外周感觉通路中诱发的传入神经信号。此外，我们已经证明了应用于结肠远端黏膜的细菌产物可诱发迷走神经传入激活。该方案可能有助于我们理解肠道-大脑通讯功能失调的功能性肠道疾病，并促进对微生物群-肠道-大脑信号传导的实时探究。
