title: Relationship between light and dark period activity cycles and oral condition in senescence-accelerated mice.
abstract: We investigated the effect of tooth absence and masticatory abnormalities due to powdered food feeding starting during the juvenile period on light and dark period activity cycles in senescence-accelerated mice (SAMP1). SAMP1 were divided into 5 groups: Group 1, maxillo-mandibular molar tooth extraction; Group 2, maxillary molar tooth extraction; Group 3, mandibular molar tooth extraction; Group 4, powdered food; and Group 5, sham-operated control. Senescence was observed earliest in the powdered food group. Total 24-hour activity was higher in the control group than in the four other groups. In the powdered food group, the dark period activity decreased to less than 60% of the total activity in the 36th week. In the tooth extraction groups (Groups 1-3), dark period activity decreased to less than 60% of the total activity in the 40th week. The control group dark period activity remained above 60% for the entire experimental period. Thus, the distinction between the light and dark periods disappeared earlier in the four experimental groups compared with the control group. Significant correlations were noted among total activity, degree of senescence, and percent dark period activity in each experimental group. Functional masticatory insufficiency promoted dementia and behavioral abnormalities in SAMP1.
authors: Department of Pediatric Dentistry, Asahi University School of Dentistry, 1851-1 Hozumi, Mizuho, Gifu, 501-0296, Japan. iinuma@dent.asahi-u.ac.jp
authors: Mitsuo
authors: M
authors: Iinuma
authors: Sayoko
authors: S
authors: Yasui
authors: Mika
authors: M
authors: Oonishi
authors: Chika
authors: C
authors: Kurata
authors: Yukiko
authors: Y
authors: Ichihashi
authors: Yasuo
authors: Y
authors: Tamura
authors: Kin-Ya
authors: KY
authors: Kubo
mesh_terms: D000375:Aging / Q000473:pathology / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D021081:Chronobiology Disorders / Q000150:complications / Q000503:physiopathology*; D003624:Darkness; D003704:Dementia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D004195:Disease Models, Animal; D008027:Light; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009066:Mouth, Edentulous / Q000150:complications / Q000503:physiopathology*