title: Functional roles of capsaicin-sensitive intrinsic neural circuit in the regulation of esophageal peristalsis in rats: in vivo studies using a novel method.
abstract: A well-developed myenteric plexus exists in the esophagus composed of striated muscle layers, but its functional role in controlling peristaltic movements remains to be clarified. The purpose of this study was to clarify the role of a local neural reflex consisting of capsaicin-sensitive primary afferent neurons and intrinsic neurons in esophageal peristalsis. We firstly devised a method to measure peristaltic movement of esophagus in vivo in rats. Rats were anesthetized with urethane, and esophageal intraluminal pressure and propelled intraluminal liquid volume were recorded. In the experimental system, an intraluminal pressure stimulus evoked periodic changes in intraluminal pressure of the esophagus, which were consistently accompanied by intraluminal liquid propulsion. Bilateral vagotomy abolished changes in intraluminal pressure as well as liquid propulsion. These results indicate that the novel method is appropriate for inducing peristalsis in the esophagus composed of striated muscles. Then, by using the method, we examined functional roles of the local reflex in esophageal peristalsis. For that purpose, we used rats in which capsaicin-sensitive neurons had been destroyed. The esophagus of capsaicin-treated rats showed a multiphasic rise in intraluminal pressure, which may due to noncoordinated contractions of esophageal muscles, whereas a monophasic response was observed in the intact rat esophagus. In addition, destruction of capsaicin-sensitive neurons increased the propelled liquid volume and lowered the pressure threshold for initiating peristalsis. These results suggest that the local neural reflex consisting of capsaicin-sensitive neurons and intrinsic neurons contributes to coordination of peristalsis and suppresses mechanosensory function of vagal afferents in the esophagus.
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Shima
authors.forename: Takahiko
authors.initials: T
authors.lastname: Shiina
authors.forename: Kiyotada
authors.initials: K
authors.lastname: Naitou
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakamori
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D004947:Esophagus / Q000187:drug effects* / Q000294:innervation*; D008297:Male; D040542:Mechanotransduction, Cellular; D009197:Myenteric Plexus / Q000187:drug effects* / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D010528:Peristalsis / Q000187:drug effects*; D011312:Pressure; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects*; D018689:Sensory System Agents / Q000494:pharmacology*; D013116:Spinal Cord / Q000601:surgery; D013997:Time Factors; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology
chemical_list: D018689:Sensory System Agents; D002211:Capsaicin
keywords: capsaicin-sensitive neuron; esophagus; in vivo system; intrinsic neuron; peristalsis