title: Emetic stimulation inhibits the swallowing reflex in decerebrate rats.
abstract: The effects of emetic stimulation on the swallowing reflex were investigated in decerebrated rats. Hypoxia, gastric distension and LiCl administration were used as emetic stimulations. The swallowing reflex was elicited by electrical stimulation of the superior laryngeal nerve (SLN, 20 Hz, 3-5 V, 0.3 ms duration) for 20 s. To examine the effect of hypoxia, nitrogen gas was inhaled under artificial ventilation. There were significantly fewer swallows during a decrease in PO(2) than under air ventilation (p<0.05). The number of swallows during 3-ml stomach distension was significantly lower than that before distension (p<0.05). Intravenous administration of LiCl (100 mg/kg) also significantly reduced the number of swallows (p<0.05). The combination of SLN stimulation and emetic stimuli occasionally produced burst activity of abdominal muscles, which might be associated with the gag reflex. Both the gag and swallowing reflexes are well known to be mediated by the nucleus of the solitary tract. The physiological roles of the gag reflex and the swallowing reflex are considered to be reciprocal. Taken together, these results suggest that emetic stimulation inhibits the swallowing pattern generator via the nucleus of the solitary tract, which in turn facilitates the gag reflex.
authors.affiliation: Department of Rehabilitation, Kawasaki University of Medical Welfare, Kurashiki 701-0193, Japan.
authors.forename: Chiharu
authors.initials: C
authors.lastname: Kurozumi
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Yamagata
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Himi
authors.forename: Tomoshige
authors.initials: T
authors.lastname: Koga
mesh_terms: D000818:Animals; D003655:Decerebrate State; D003679:Deglutition / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D004639:Emetics / Q000494:pharmacology*; D005683:Gagging / Q000187:drug effects / Q000502:physiology; D000860:Hypoxia; D007821:Laryngeal Muscles / Q000294:innervation / Q000503:physiopathology; D007823:Laryngeal Nerves / Q000502:physiology; D018021:Lithium Chloride / Q000494:pharmacology*; D008526:Medulla Oblongata / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009415:Nerve Net / Q000502:physiology; D010614:Pharynx / Q000294:innervation / Q000502:physiology; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology; D013268:Stimulation, Chemical; D013270:Stomach / Q000294:innervation / Q000502:physiology; D014839:Vomiting / Q000139:chemically induced
chemical_list: D004639:Emetics; D018021:Lithium Chloride