title: Malocclusion induces chronic stress.
abstract: We examined the effect of occlusal disharmony in senescence-accelerated (SAMP8) mice on plasma corticosterone levels, spatial learning in the water maze, fos induction, hippocampal neuron number, expression of glucocorticoid receptors (GR) and glucocorticoid receptor messenger ribonucleic acid (GRmRNA) in hippocampus and inhibitor of glucocorticoid (metyrapone). Bite-raised aged mice had significantly greater plasma corticosterone levels than age-matched control mice as well as impaired spatial memory and decreased Fos induction and a number of neurons in hippocampus. GR and GRmRNA expressions were significantly decreased in aged bite-raised mice compared with age-matched control mice. Pretreatment with metyrapone inhibited not only the bite-raised induced increase in plasma corticosterone levels, but also the reduction in the number of hippocampal neurons and impaired spatial learning. These datas suggest that the bite-raised condition may enhance the aging process in hippocampus, thereby leading to impairment of spatial memory by stress.
authors.affiliation: Department of Pediatric Dentistry, Division of Oral Structure, Function and Development, Mizuho, Gifu 501-0296, Japan. iinuma@dent.asahi-u.ac.jp
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Iinuma
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Ichihashi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hioki
authors.forename: Chika
authors.initials: C
authors.lastname: Kurata
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Tamura
authors.forename: Kin-ya
authors.initials: KY
authors.lastname: Kubo
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D005938:Glucocorticoids / Q000037:antagonists & inhibitors / Q000097:blood*; D006624:Hippocampus / Q000166:cytology / Q000503:physiopathology*; D008310:Malocclusion / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D008568:Memory / Q000502:physiology*; D051379:Mice; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D013037:Spatial Behavior / Q000502:physiology; D013312:Stress, Physiological / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology
chemical_list: D005938:Glucocorticoids; D016760:Proto-Oncogene Proteins c-fos; D011965:Receptors, Glucocorticoid