title: Disruption of programmed masticatory movements in unilateral MPTP-treated monkeys as a model of jaw movement abnormality in Parkinson's disease.
abstract: While motor disturbance in Parkinson's disease can affect innate, programmed processes, such as masticatory mandibular movements, the pathophysiology of such abnormalities remains unclear. This study applies digital analysis by high-speed video signal processing that tracks three dots placed around the mouth for recording masticatory movements in unilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys. The system analyzes displacement, velocity and cycle duration of the topography of mandibular movement during mastication of sweet potato slices. In monkeys receiving MPTP into the right carotid artery (n = 3), positron emission tomography indicated significant reduction in the binding of (E)-N-(3-iodoprop-2-enyl)-2β-carbo[(11)C]methoxy-3β-(4-methylphenyl)nortropane ([(11)C]PE2I) to the dopamine transporter in the right caudate, putamen, nucleus accumbens and substantia nigra relative to the contralateral hemisphere. These monkeys showed hypokinesia of the left forelimbs and hindlimbs. During mastication, MPTP-treated monkeys chewed preferentially on the left side, while untreated monkeys (n = 3) showed no preference for chewing side. The amplitude of vertical opening and closing movements was reduced in MPTP-treated monkeys, with a slight but significant increase in the lateral component of mandibular movements. The velocity of all phases of horizontal mandibular movements was reduced. In consequence, duration of the occlusal phase was increased, while duration of the closing phase was decreased in MPTP-treated monkeys. These findings indicate that during masticatory movements MPTP-treated monkeys chew preferentially on the side contralateral to loss of dopamine neurons, with reduced amplitude and velocity of mandibular movements. High-speed digital movement analysis is able to define and quantify abnormalities of orofacial movement topography as a sign of parkinsonism.
authors.affiliation: Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo, Japan. k-adachi@dent.meikai.ac.jp
authors.forename: Kazunori
authors.initials: K
authors.lastname: Adachi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Chihiro
authors.initials: C
authors.lastname: Yokoyama
authors.forename: John L
authors.initials: JL
authors.lastname: Waddington
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakagami
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Onoe
authors.forename: Noriaki
authors.initials: N
authors.lastname: Koshikawa
mesh_terms: D000818:Animals; D007839:Functional Laterality / Q000502:physiology*; D008252:Macaca fascicularis; D008297:Male; D008409:Mastication / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009069:Movement Disorders / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D020734:Parkinsonian Disorders / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D049268:Positron-Emission Tomography