title: Occlusal disharmony accelerates the initiation of atherosclerosis in apoE knockout rats.
abstract: BACKGROUND
  Psychosocial stress is one of the risk factors for atherosclerosis. As occlusal disharmony induces psychological stress, we hypothesized that psychological stress by occlusal disharmony accelerates atherosclerosis. The aim of this study was to investigate the effects of occlusal disharmony on the initiation of atherosclerosis in apolipoprotein E (apoE) knockout rats.
  
  
  METHODS
  Fourteen male apoE-knockout rats (age; 8 weeks) (Sprague-Dawley strain background) were divided into two groups of seven rats: the occlusal disharmony group and the no treatment (control) group. In the occlusal disharmony group, the maxillary molar cusps were cut off for the 8-week experimental period.
  
  
  RESULTS
  In the occlusal disharmony group, the percentages of the area of total aortic lumen occupied by plaques and lipid were significantly higher than those in the control group (p < 0.05, t-test). The occlusal disharmony group also showed significantly higher serum levels of very low-density lipoprotein-cholesterol (VLDL) and low-density lipoprotein-cholesterol (LDL), plasma levels of corticosterone (1.9, 1.3 and 1.3 times, respectively), higher aortic protein expression levels of vascular cell adhesion molecule-1 (VCAM1) and intercellular adhesion molecule-1 (ICAM1) (1.5 and 1.4 times, respectively), and higher aortic gene expression of levels of VCAM1 and Toll-like receptor 4 (TLR4) (1.9 and 4.3 times, respectively), as compared to the control group (p < 0.05). However, there were no significant differences in serum levels of oxidized LDL, reactive oxygen metabolites and C-reactive protein between the two groups.
  
  
  CONCLUSIONS
  In apoE knockout rats, occlusal disharmony may induce VCAM1, ICAM1 and TLR4 expression and accelerate the initiation of atherosclerosis.
authors.affiliation: Department of Preventive Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan. dekuni7@md.okayama-u.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ekuni
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yoneda
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Endo
authors.forename: Kenta
authors.initials: K
authors.lastname: Kasuyama
authors.forename: Koichiro
authors.initials: K
authors.lastname: Irie
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Mizutani
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Azuma
authors.forename: Takaaki
authors.initials: T
authors.lastname: Tomofuji
authors.forename: Manabu
authors.initials: M
authors.lastname: Morita
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000276:immunology / Q000473:pathology; D001057:Apolipoproteins E / Q000235:genetics*; D050197:Atherosclerosis / Q000097:blood / Q000276:immunology / Q000523:psychology*; D002097:C-Reactive Protein / Q000378:metabolism; D055786:Gene Knockout Techniques; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008264:Macrophages / Q000276:immunology; D008297:Male; D058226:Plaque, Atherosclerotic / Q000276:immunology / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D055647:Rats, Transgenic; D017382:Reactive Oxygen Species / Q000097:blood; D013315:Stress, Psychological / Q000097:blood / Q000150:complications* / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: D001057:Apolipoproteins E; D017382:Reactive Oxygen Species; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D002097:C-Reactive Protein