title: Serotonin-induced contractile responses of esophageal smooth muscle in the house musk shrew (Suncus murinus).
abstract: BACKGROUND
  Serotonin (5-hydroxytryptamine, 5-HT) is a regulatory factor in motility of the gastrointestinal tract including the esophagus. Although we proposed that vagal cholinergic and mast cell-derived non-cholinergic components including serotonin coordinately shorten the esophagus, the precise mechanism of serotonin-induced contractions in the suncus esophagus is still unclear. Therefore, the aims of this study were to determine characteristics of contractile responses induced by serotonin and to identify 5-HT receptor subtypes responsible for regulating motility in the suncus esophagus.
  
  
  METHODS
  An isolated segment of the suncus esophagus was placed in an organ bath, and longitudinal or circular mechanical responses were recorded using a force transducer.
  
  
  RESULTS
  Serotonin evoked contractile responses of the suncus esophagus in the longitudinal direction but not in the circular direction. Tetrodotoxin did not affect the serotonin-induced contractions. Pretreatment with a non-selective 5-HT receptor antagonist or double application of 5-HT1and 5-HT2receptor antagonists blocked the serotonin-induced contractions. 5-HT1and 5-HT2receptor agonists, but not a 5-HT3receptor agonist, evoked contractile responses in the suncus esophagus.
  
  
  CONCLUSIONS
  The findings suggest that serotonin induces contractile responses of the longitudinal smooth muscle in the muscularis mucosae of the suncus esophagus that are mediated via 5-HT1and 5-HT2receptors on muscle cells. The serotonin-induced contractions might contribute to esophageal peristalsis and emetic response.
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan. tshiina@gifu-u.ac.jp.
authors.forename: T
authors.initials: T
authors.lastname: Shiina
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Naitou
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nakamori
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Horii
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Sano
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Shimaoka
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology*; D009924:Organ Culture Techniques; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D012788:Shrews
chemical_list: D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin
keywords: esophagus; house musk shrew; serotonin; smooth muscle