Differential activation of medullary vagal nuclei caused by stimulation of different esophageal mechanoreceptors.
Esophageal mechanoreceptors, i.e. muscular slowly adapting tension receptors and mucosal rapidly adapting touch receptors, mediate different sets of reflexes. The aim of this study was to determine the medullary vagal nuclei involved in the reflex responses to activation of these receptors. Thirty-three cats were anesthetized with alpha-chloralose and the esophagus was stimulated by slow balloon or rapid air distension. The physiological effects of the stimuli (N=4) were identified by recording responses from the pharyngeal, laryngeal, and hyoid muscles, esophagus, and the lower esophageal sphincter (LES). The effects on the medullary vagal nuclei of the stimuli: slow distension (N=10), rapid distension (N=9), and in control animals (N=10) were identified using the immunohistochemical analysis of c-fos. The experimental groups were stimulated three times per minute for 3h. After the experiment, the brains were removed and processed for c-fos immunoreactivity or thioinin. We found that slow balloon distension activated the esophago-UES contractile reflex and esophago-LES relaxation response, and rapid air injection activated the belch and its component reflexes. Slow balloon distension activated the NTSce, NTSdl, NTSvl, DMNc, DMNr and NAr; and rapid air injection primarily activated AP, NTScd, NTSim, NTSis, NTSdm, NTSvl, NAc and NAr. We concluded that different sets of medullary vagal nuclei mediate different reflexes of the esophagus activated from different sets of mechanoreceptors. The NTScd is the primary NTS subnucleus mediating reflexes from the mucosal rapidly adapting touch receptors, and the NTSce is the primary NTS subnucleus mediating reflexes from the muscular slowly adapting tension receptors. The AP may be involved in mediation of belching.
Division of Gastroenterology and Hepatology, MCW Dysphagia Research Laboratory, MFRB 4066, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA. imlang@mcw.edu
Ivan M
IM
Lang
Bidyut K
BK
Medda
Reza
R
Shaker
D000818:Animals; D001921:Brain / Q000378:metabolism; D002415:Cats; D049630:Esophageal Sphincter, Lower; D004947:Esophagus / Q000502:physiology; D005260:Female; D007150:Immunohistochemistry; D007821:Laryngeal Muscles / Q000502:physiology; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D008526:Medulla Oblongata / Q000166:cytology; D009046:Motor Neurons / Q000378:metabolism*; D009119:Muscle Contraction / Q000502:physiology*; D010609:Pharyngeal Muscles / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D017552:Solitary Nucleus / Q000378:metabolism*; D014630:Vagus Nerve / Q000502:physiology
D016760:Proto-Oncogene Proteins c-fos