title: Central orexin inhibits reflex swallowing elicited by the superior laryngeal nerve via caudal brainstem in the rat.
abstract: We examined the effects of orexins on the reflex swallowing using anesthetized rats. Orexins were administered into the fourth ventricle. Swallowing was induced by repeated electrical stimulation of the central cut end of the superior laryngeal nerve (SLN) and was identified by the electromyogram lead penetrated the mylohyoid muscle through bipolar electrodes. The frequency of swallowing during the electrical stimulation of the SLN decreased after the administration of orexin-A in a dose-dependent manner. The latency of the first swallowing tended to be extended after the administration of orexin-A. The administration of orexin-B did not affect swallowing frequency. Pre-administration of SB334867, an orexin-1 receptor antagonist, attenuated the degree of inhibition of swallowing frequency induced by the administration of orexin-A. To identify the effective site of orexin-A, the effect of a microinjection of orexin-A into the dorsal vagal complex (DVC) was evaluated. Orexin-A was injected into one of the lateral DVC, the intermediate DVC, or the medial DVC. Microinjection of orexin-A into the medial DVC but not the other two sites decreased swallowing frequency. Pre-injection of SB334867 into the medial DVC disrupted the inhibitory response induced by fourth ventricular administration of orexin-A. The electrical lesion of the commissural part of the NTS, but not ablation of the AP, abolished the inhibition of reflex swallowing induced by fourth ventricular administration of orexin-A. These results suggest that orexin-A inhibits reflex swallowing via orexin-1 receptors situated in the commissural part of the NTS and/or its vicinity.
authors.affiliation: Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan.. Electronic address: mkobashi@md.okayama-u.ac.jp.
authors.forename: Motoi
authors.initials: M
authors.lastname: Kobashi
authors.affiliation: Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mizutani
authors.affiliation: Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Fujita
authors.affiliation: Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mitoh
authors.affiliation: Biomedical Engineering Department, Tokyo City University, Tokyo 158-8557, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Shimatani
authors.affiliation: Department of Oral Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8525, Japan.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Matsuo
mesh_terms: D000818:Animals; D001583:Benzoxazoles / Q000494:pharmacology; D001933:Brain Stem / Q000187:drug effects / Q000502:physiology*; D002491:Central Nervous System Agents / Q000494:pharmacology; D003679:Deglutition / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D047908:Intracellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000378:metabolism*; D007823:Laryngeal Nerves / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D009287:Naphthyridines; D009479:Neuropeptides / Q000008:administration & dosage / Q000378:metabolism*; D000068796:Orexin Receptor Antagonists; D064446:Orexin Receptors / Q000378:metabolism*; D000068797:Orexins; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; D001583:Benzoxazoles; D002491:Central Nervous System Agents; C578627:Hcrtr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009287:Naphthyridines; D009479:Neuropeptides; D000068796:Orexin Receptor Antagonists; D064446:Orexin Receptors; D000068797:Orexins; D014508:Urea
keywords: Area postrema; Commissural NTS; Orexins; SB334867; Swallowing