Chemosensitivity of unmyelinated axons in isolated human gastric vagus nerve

• Published in: Autonomic neuroscience 2007-10, Vol.136 (1), p.100-104
• Main Authors: Lang, Philip M, Grafe, Peter
• Format: Article
• Language: English
• Subjects: 5-HT3; Action Potentials - drug effects; Action Potentials - physiology; Advanced Basic Science; Aged; Axons - drug effects; Axons - physiology; Biological and medical sciences; Capsaicin - pharmacology; Cell Membrane - drug effects; Cell Membrane - physiology; Chemoreceptor Cells - drug effects; Chemoreceptor Cells - physiology; Excitability; Female; Fundamental and applied biological sciences. Psychology; Gastric Mucosa - innervation; Gastric Mucosa - physiology; Humans; Male; Medical Education; Membrane Potentials - drug effects; Membrane Potentials - physiology; Middle Aged; nAChR; Nerve Fibers, Unmyelinated - drug effects; Nerve Fibers, Unmyelinated - physiology; Neurons, Afferent - drug effects; Neurons, Afferent - physiology; Nicotinic Agonists - pharmacology; Nodose Ganglion - drug effects; Nodose Ganglion - physiology; Organ Culture Techniques; Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ; Receptors, Nicotinic - drug effects; Receptors, Nicotinic - physiology; Receptors, Serotonin, 5-HT3 - drug effects; Receptors, Serotonin, 5-HT3 - physiology; Serotonin Receptor Agonists - pharmacology; TRPV Cation Channels - drug effects; TRPV Cation Channels - physiology; TRPV1; Unmyelinated axons; Vagus nerve; Vagus Nerve - drug effects; Vagus Nerve - physiology; Vertebrates: nervous system and sense organs; Visceral Afferents - drug effects; Visceral Afferents - physiology
• ISSN: 1566-0702; 1872-7484
• DOI: 10.1016/j.autneu.2007.05.001

Abstract Vagal afferent neurons from the stomach may be activated not only by chemical stimuli in the mucosa but also by circulating factors. In the present study, we have used electrophysiological techniques to characterize functional activity of several receptors for chemical mediators on unmyelinated axons in isolated fascicles of human gastric vagus nerve. Application of agonists at the nicotinic acetylcholine receptor (nAChR), 5-HT3 subtype of serotonin receptor, and the transient receptor potential vanilloid receptor-1 (TRPV1) resulted in a change in the height and/or threshold of the C-fiber compound action potential. These effects were blocked by specific antagonists of nAChR (mecamylamine), 5-HT3 (Y-25130), and TRPV1 (capsazepine). We conclude that the chemosensitivity of unmyelinated vagal axons can be studied using isolated segments of human gastric vagus nerve. The presence of receptors indicates that circulating factors may modify vagal afferent neurons also by effects on the axonal membrane.