title: Forced mastication increases survival of adult neural stem cells in             the hippocampal dentate gyrus.
abstract: In this study, we examined the effect of forced mastication on neurogenesis in the hippocampal dentate gyrus (DG) of adult mice. Six-week-old mice were subjected to either a hard or normal diet for 13 weeks. They received a daily injection of bromodeoxyuridine (BrdU) for 12 consecutive days beginning at 14 weeks of age. The number of BrdU-positive cells in the DG was counted 1 day after and 5 weeks after the final BrdU injection. The number of BrdU-positive cells 1 day after injection did not differ between the 2 diet groups. However, the number of BrdU-positive cells in the group fed the hard diet was significantly increased 5 weeks after BrdU injection compared to the group fed the normal diet. The results of the Morris water maze test showed that mice fed a hard diet required significantly less time to reach the platform than the control mice when tested at 10 days. Moreover, mice in the group fed the hard diet spent significantly more time in the former platform area than the group fed the normal diet, indicating that hard diet feeding improved spatial memory compared to normal diet feeding. Real-time PCR analysis showed that the expression of glutamate receptor 1 mRNA was significantly increased in the group fed the hard diet compared with the group fed the normal diet. These results suggest that mastication increases the survival of adult neural stem cells in the hippocampal DG.
authors.affiliation: Department of Pediatric Dentistry, Tokushima University Hospital,                     Tokushima 770‑8504, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Akazawa
authors.forename: Takamasa
authors.initials: T
authors.lastname: Kitamura
authors.forename: Yuri
authors.initials: Y
authors.lastname: Fujihara
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Masato
authors.initials: M
authors.lastname: Mitome
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D053687:Adult Stem Cells / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D049109:Cell Proliferation; D002470:Cell Survival; D018891:Dentate Gyrus / Q000166:cytology* / Q000378:metabolism; D004032:Diet; D004435:Eating; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008409:Mastication; D051379:Mice; D008810:Mice, Inbred C57BL; D009414:Nerve Growth Factors / Q000235:genetics; D058953:Neural Stem Cells / Q000166:cytology* / Q000378:metabolism; D055495:Neurogenesis; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D009414:Nerve Growth Factors; D012333:RNA, Messenger