title: Chewing ameliorates chronic mild stress-induced bone loss in senescence-accelerated mouse (SAMP8), a murine model of senile osteoporosis.
abstract: Chronic mild stress is a risk factor for osteoporosis and chewing inhibits the stress response. We examined the effect of chewing on chronic stress-induced bone loss and bone microstructural deterioration in mice. The senescence-accelerated mouse strain P8 (SAMP8) was randomly divided into control, stress, and stress with chewing groups of fifteen animals each. Mice in the stress and stress with chewing groups were placed in a ventilated restraint tube for 60minutes, twice a day for 4weeks. The restrained mice were simultaneously subjected daily to one of the following stressors: water immersion, physical shaking and flashing lights. Mice in the stress with chewing group were allowed to chew a wooden stick during the experimental period. After the experiment, the bone response was evaluated using quantitative micro computed tomography, bone histomorphometry, and biochemical markers. Exposure of SAMP8 mice to chronic stress resulted in significant increase of the blood corticosterone and noradrenaline levels, and adrenal weight. The bone resorption was activated and the bone formation was suppressed. Trabecular bone volume and trabecular number were decreased in both the vertebra and distal femur of the stress group. Chewing under chronic stress prevented the increase in the blood corticosterone and noradrenaline levels, attenuated the reduced bone formation and increased bone resorption, improved the trabecular bone loss and bone microstructural deterioration induced by chronic mild stress. These findings indicate that chewing can ameliorate chronic stress-induced bone loss in SAMP8 mice. Thus, chewing may represent a useful method preventing and/or treating chronic stress-related osteoporosis.
authors.affiliation: Department of Prosthodontics, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu, 501-0296, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Furuzawa
authors.affiliation: Department of Anatomy, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. Electronic address: huayue@gifu-u.ac.jp.
authors.forename: Huayue
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Prosthodontics, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu, 501-0296, Japan.
authors.forename: Shu
authors.initials: S
authors.lastname: Fujiwara
authors.affiliation: Department of Anatomy and Physiology, Faculty of Domesticeconomy, Nagoya Women's University, Nagoya, Aichi, 476-8610, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Seijoh University Graduate School of Health Care Studies, Tokai, Aichi, 476-8588, Japan.
authors.forename: Kin-ya
authors.initials: KY
authors.lastname: Kubo
mesh_terms: D000311:Adrenal Glands / Q000473:pathology; D000375:Aging / Q000502:physiology*; D019588:Aging, Premature / Q000097:blood / Q000150:complications / Q000503:physiopathology; D000818:Animals; D016723:Bone Remodeling / Q000502:physiology; D002908:Chronic Disease; D003345:Corticosterone / Q000097:blood; D004195:Disease Models, Animal; D021621:Imaging, Three-Dimensional / Q000379:methods; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000648:ultrastructure; D008297:Male; D008409:Mastication / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D009638:Norepinephrine / Q000097:blood; D009929:Organ Size / Q000502:physiology; D010024:Osteoporosis / Q000097:blood / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D013314:Stress, Mechanical; D013315:Stress, Psychological / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D055114:X-Ray Microtomography
chemical_list: D003345:Corticosterone; D009638:Norepinephrine
keywords: Bone histomorphometry; Chewing; Chronic mild stress; Micro-CT; Osteoporosis; SAMP8