title: Changes in the frequency of swallowing during electrical stimulation of superior laryngeal nerve in rats.
abstract: The aim of the present study was to investigate the adaptation of the swallowing reflex in terms of reduced swallowing reflex initiation following continuous superior laryngeal nerve stimulation. Forty-four male Sprague Dawley rats were anesthetized with urethane. To identify swallowing, electromyographic activity of the left mylohyoid and thyrohyoid muscles was recorded. To evoke the swallowing response, the superior laryngeal nerve (SLN), recurrent laryngeal nerve, or cortical swallowing area was electrically stimulated. Repetitive swallowing evoked by continuous SLN stimulation was gradually reduced, and this reduction was dependent on the resting time duration between stimulations. Prior SLN stimulation also suppressed subsequent swallowing initiation. The reduction in evoked swallows induced by recurrent laryngeal nerve or cortical swallowing area stimulation was less than that following superior laryngeal nerve stimulation. Decerebration had no effect on the reduction in evoked swallows. Prior subthreshold stimulation reduced subsequent initiation of swallowing, suggesting that there was no relationship between swallowing movement evoked by prior stimulation and the subsequent reduction in swallowing initiation. Overall, these data suggest that reduced sensory afferent nerve firing and/or trans-synaptic responses, as well as part of the brainstem central pattern generator, are involved in adaptation of the swallowing reflex following continuous stimulation of swallow-inducing peripheral nerves and cortical areas.
authors.affiliation: Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata 951-8514, Japan. Electronic address: k-tsuji@dent.niigata-u.ac.jp.
authors.forename: Kojun
authors.initials: K
authors.lastname: Tsuji
authors.affiliation: Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata 951-8514, Japan. Electronic address: tsujimura@dent.niigata-u.ac.jp.
authors.forename: Takanori
authors.initials: T
authors.lastname: Tsujimura
authors.affiliation: Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata 951-8514, Japan. Electronic address: jin-m@dent.niigata-u.ac.jp.
authors.forename: Jin
authors.initials: J
authors.lastname: Magara
authors.affiliation: Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata 951-8514, Japan. Electronic address: s-sakai@dent.niigata-u.ac.jp.
authors.forename: Shogo
authors.initials: S
authors.lastname: Sakai
authors.affiliation: Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata 951-8514, Japan. Electronic address: nakayuki@dent.niigata-u.ac.jp.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata 951-8514, Japan. Electronic address: inoue@dent.niigata-u.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Inoue
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology; D003679:Deglutition; D004558:Electric Stimulation; D007823:Laryngeal Nerves / Q000502:physiology*; D008297:Male; D009334:Neck Muscles / Q000294:innervation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology*
keywords: Central pattern generator; Nucleus tractus solitarii; Rat; Superior laryngeal nerve; Swallowing