title: Differential involvement of two cortical masticatory areas in submandibular salivary secretion in rats.
abstract: To evaluate the role of the masticatory area in the cerebral cortex in the masticatory-salivary reflex, we investigated submandibular salivary secretion, jaw-movement trajectory and electromyographic activity of the jaw-opener (digastric) and jaw-closer (masseter) muscles evoked by repetitive electrical stimulation of the cortical masticatory area in anesthetized rats. Rats have two cortical masticatory areas: the anterior area (A-area) in the orofacial motor cortex, and the posterior area (P-area) in the insular cortex. Our defined P-area extended more caudally than the previous reported one. P-area stimulation induced vigorous salivary secretion (about 20 µl/min) and rhythmical jaw movements (3-4 Hz) resembling masticatory movements. Salivary flow persisted even after minimizing jaw movements by curarization. A-area stimulation induced small and fast rhythmical jaw movements (6-8 Hz) resembling licking of solutions, but not salivary secretion. These findings suggest that P-area controls salivary secretion as well as mastication, and may be involved in the masticatory-salivary reflex.
authors.affiliation: Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Maeda
authors.affiliation: Department of Oral Physiology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
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, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mitoh
authors.affiliation: Department of Oral Physiology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Fujita
authors.affiliation: Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Minagi
authors.affiliation: Department of Oral Physiology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan. Electronic address: rmatsuo@md.okayama-u.ac.jp.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Matsuo
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D008297:Male; D008406:Masseter Muscle / Q000502:physiology; D008409:Mastication / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement; D010507:Periodicity; D051381:Rats; D017208:Rats, Wistar; D012472:Salivation; D013363:Submandibular Gland / Q000378:metabolism*
keywords: Cerebral cortex; EMG; Jaw movements; Rat; Salivary secretion