title: Regulation of longitudinal esophageal motility in the house musk shrew (Suncus murinus).
abstract: Suncus murinus (house musk shrew; suncus) is a species of insectivore that has an ability to vomit. Although longitudinal movement of the esophagus would be related to the emetic response, regulatory mechanisms for the suncus esophageal motility are unclear. Therefore, the aim of the present study was to clarify components that regulate esophageal motility in the suncus. An isolated segment of the suncus esophagus was placed in an organ bath, and longitudinal mechanical responses were recorded using a force transducer. Electrical stimulation of the vagus trunk evoked a biphasic contractile response. The first phase of the contractile response was blocked by α-bungarotoxin, a blocker of nicotinic acetylcholine receptors on striated muscle cells, whereas the second one was blocked by atropine, a blocker of muscarinic acetylcholine receptors on smooth muscle cells. Next, we investigated whether mast cells are involved in motor functions of the suncus esophagus. Application of a mast cell stimulator, compound 48/80, elicited contractile responses, which was resistant to tetrodotoxin. Exogenous application of serotonin and histamine induced contractile responses. The mast cell activation-mediated contraction was abolished by double desensitization by serotonin and histamine and pre-treatment with indomethacin, a cyclooxygenase inhibitor. The findings show that cholinergic and non-cholinergic transmitters induce longitudinal contraction in the suncus esophagus, which might contribute to esophageal shortening during emesis. Cholinergic transmitters are derived from vagal efferents, and non-cholinergic transmitters, which are thought to be serotonin, histamine and prostaglandins, are released from mast cells.
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Japan. Electronic address: tshiina@gifu-u.ac.jp.
authors.forename: Takahiko
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, Japan.
authors.forename: Kiyotada
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, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakamori
authors.affiliation: Laboratory of Pathology, Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sakai
authors.affiliation: Laboratory of Physiology, Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Japan.
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Shimizu
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D004947:Esophagus / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006632:Histamine / Q000378:metabolism; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D054792:Muscle, Striated / Q000187:drug effects / Q000502:physiology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D012788:Shrews; D046509:Tissue Culture Techniques; D014630:Vagus Nerve / Q000502:physiology; D014839:Vomiting / Q000503:physiopathology*
chemical_list: D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D012701:Serotonin; D006632:Histamine; D011451:Prostaglandin-Endoperoxide Synthases; D000109:Acetylcholine
keywords: Esophagus; Histamine; Mast cell; Prostaglandin; Serotonin