title: Cell proliferation in the dentate gyrus of rat hippocampus is inhibited by soft diet feeding.
abstract: BACKGROUND
  Recently it has become well accepted that neurogenesis occurs in the dentate gyrus of the hippocampus, a region important to memory and learning function in rodents and humans. Reports show that neurogenesis in the hippocampus is regulated by certain factors, such as exposure to an enriched environment, physical activity, aging and stress. The relationship between the change in the task of chewing as one oral environmental factor, and the mechanisms of hippocampal neuron generation are unclear.
  
  
  OBJECTIVE
  We examined whether cell proliferation varies by chewing tasks with different food textures in the dentate gyrus of the rat hippocampus.
  
  
  METHODS
  Wistar rats were divided into two groups, one was fed a solid diet, known as the hard-diet feeding group, and the soft-diet feeding group, which was fed a powder diet containing the same components as the solid one for 3, 7, 16 and 24 weeks. Thymidine analog 5-bromo-2'-deoxyuridine (BrdU) was used as a marker of cell proliferation within the dentate gyrus of the hippocampus and olfactory bulb.
  
  
  RESULTS
  The results of this study indicated that the total number of BrdU-positive cells in the hippocampal dentate gyrus significantly decreased with aging and were significantly fewer in the soft-diet feeding group than in hard-diet feeding group in 7-, 16- and 24-week-old rats after the BrdU injection. The change of BrdU-positive cell expression between soft and hard diets in 3- and 24-week-old rats was not observed in the olfactory bulb.
  
  
  CONCLUSIONS
  It has been suggested that cell proliferation in the dentate gyrus of the rat hippocampus is characteristically suppressed by soft diet feeding.
authors.affiliation: Department of Oral and Maxillofacial Rehabilitation, Kanagawa Dental College, Yokosuka, Kanagawa, Japan.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Aoki
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kimoto
authors.forename: Norio
authors.initials: N
authors.lastname: Hori
authors.forename: Minoru
authors.initials: M
authors.lastname: Toyoda
mesh_terms: D000375:Aging / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D049109:Cell Proliferation; D018891:Dentate Gyrus / Q000166:cytology* / Q000378:metabolism; D004032:Diet; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008409:Mastication / Q000502:physiology; D009066:Mouth, Edentulous / Q000473:pathology; D009830:Olfactory Bulb / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001973:Bromodeoxyuridine