title: Effects of occlusal disharmony on the hippocampal dentate gyrus in aged senescence-accelerated mouse prone 8 (SAMP8).
abstract: OBJECTIVE
  Malocclusion induced by raising the bite causes chronic stress. Chronic stress leads to increased plasma corticosterone levels and impaired hippocampal function due to impaired neurogenesis or increased apoptosis in the hippocampus. The present study aimed to clarify the mechanisms underlying the impaired hippocampal function induced by the bite-raised condition in aged senescence-accelerated mouse prone 8 (SAMP8).
  
  
  METHODS
  Nine-month-old aged SAMP8 mice were randomly divided into control and bite-raised groups. The vertical dimension of the bite was raised by applying resin to the molars. We evaluated newborn cell proliferation, survival, differentiation, and apoptosis in the hippocampal dentate gyrus (DG). Hippocampal brain-derived neurotrophic factor (BDNF) levels were also measured.
  
  
  RESULTS
  The bite-raised mice exhibited a significant decrease in proliferation, survival, and differentiation of newborn cells into neurons in the hippocampal DG compared with controls. The number of apoptotic cells in the hippocampal DG was increased at 7 and 14 days after the bite-raising procedure. Expression of BDNF protein and mRNA in the hippocampus was also decreased in the bite-raised mice.
  
  
  CONCLUSIONS
  Bite-raised aged SAMP8 mice exhibited decreased neurogenesis, increased apoptosis in the hippocampal DG, and decreased hippocampal BDNF expression, in association with hippocampus-dependent learning and memory deficits.
authors.affiliation: Department of Prosthodontics, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu 501-0296, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Mori
authors.affiliation: Department of Prosthodontics, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu 501-0296, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Miyake
authors.affiliation: Division of Biochemistry, Fujita Memorial Nanakuri Institute, Fujita Health University, 1865 Hisai-isshiki-cho, Tsu, Mie 514-1296, Japan.
authors.forename: Kenmei
authors.initials: K
authors.lastname: Mizutani
authors.affiliation: Division of Biochemistry, Fujita Memorial Nanakuri Institute, Fujita Health University, 1865 Hisai-isshiki-cho, Tsu, Mie 514-1296, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Shimpo
authors.affiliation: Division of Biochemistry, Fujita Memorial Nanakuri Institute, Fujita Health University, 1865 Hisai-isshiki-cho, Tsu, Mie 514-1296, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Sonoda
authors.affiliation: Department of Human Biology, Kanagawa Dental College, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Prosthodontics, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu 501-0296, Japan.
authors.forename: Shuu
authors.initials: S
authors.lastname: Fujiwara
authors.affiliation: Seijoh University Graduate School of Health Care Studies, 2-172, Fukinodai, Tokai, Aichi, 476-8588, Japan. Electronic address: kubo@seijoh-u.ac.jp.
authors.forename: Kin-ya
authors.initials: KY
authors.lastname: Kubo
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D019208:Brain-Derived Neurotrophic Factor / Q000032:analysis / Q000096:biosynthesis; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D018891:Dentate Gyrus / Q000166:cytology / Q000378:metabolism / Q000503:physiopathology*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism / Q000503:physiopathology*; D008310:Malocclusion / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D008569:Memory Disorders / Q000208:ethnology; D051379:Mice; D008817:Mice, Mutant Strains; D008963:Molar / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D055495:Neurogenesis; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D013315:Stress, Psychological / Q000150:complications*; D014716:Vertical Dimension
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger
keywords: Apoptosis; BDNF; Hippocampus; Malocclusion; Neurogenesis