title: Responses and afferent pathways of C1-C2 spinal neurons to cervical and thoracic esophageal stimulation in rats.
abstract: Because vagal and sympathetic inputs activate upper cervical spinal neurons, we hypothesized that stimulation of the esophagus would activate C(1)-C(2) neurons. This study examined responses of C(1)-C(2) spinal neurons to cervical and thoracic esophageal distension (CED, TED) and afferent pathways for CED and TED inputs to C(1)-C(2) spinal neurons. Extracellular potentials of single C(1)-C(2) spinal neurons were recorded in pentobarbital-anesthetized male rats. Graded CED or TED was produced by water inflation (0.1-0.5 ml) of a latex balloon. CED changed activity of 48/219 (22%) neurons; 34 were excited (E), 12 were inhibited (I), and 2 were E-I. CED elicited responses for 18/18 neurons tested after ipsilateral cervical vagotomy, for 12/14 neurons tested after bilateral vagotomy and for 9/11 neurons tested after bilateral vagotomy and C(6)-C(7) spinal cord transection. TED changed activity of 31/190 (16%) neurons (28E, 3 I). Ipsilateral cervical vagotomy abolished TED-evoked responses of 5/12 neurons. Bilateral vagotomy eliminated responses of 2/4 neurons tested, and C(6)-C(7) spinal transection plus bilateral vagotomy eliminated responses of 2/2 neurons. Thus inputs from CED to C(1)-C(2) neurons most likely entered upper cervical dorsal roots, whereas inputs from TED were dependent on vagal pathways and/or sympathetic afferent pathways that entered the thoracic dorsal roots. These results supported a concept that C(1)-C(2) spinal neurons play a role in integrating visceral information from cervical and thoracic esophagus.
authors.affiliation: Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA. chao-qin@ouhsc.edu
authors.forename: Chao
authors.initials: C
authors.lastname: Qin
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Chandler
authors.forename: Chuanchau J
authors.initials: CJ
authors.lastname: Jou
authors.forename: Robert D
authors.initials: RD
authors.lastname: Foreman
mesh_terms: D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D002574:Cervical Vertebrae; D004431:Ear, External / Q000294:innervation; D004947:Esophagus / Q000502:physiology*; D006257:Head / Q000294:innervation; D008297:Male; D009333:Neck / Q000294:innervation; D009474:Neurons / Q000502:physiology*; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012782:Shoulder / Q000294:innervation; D012867:Skin / Q000294:innervation; D013116:Spinal Cord / Q000166:cytology* / Q000502:physiology*; D013238:Stereotaxic Techniques; D013904:Thoracic Vertebrae; D014630:Vagus Nerve / Q000502:physiology