Occlusal disharmony induces BDNF level in rat submandibular gland.
OBJECTIVE
brain-derived neurotrophic factor (BDNF), which is produced in rat submandibular gland, is one of the most abundant neurotrophins in the central nervous system. It is generally accepted that occlusal disharmony causes stress. The purpose of the present study was to investigate whether occlusal disharmony-induced chronic stress affects BDNF levels and morphology in rat submandibular gland.


METHODS
eight wks old male Wistar rats (n=21) were randomly divided into three groups of 7 rats. In a control (C) group, the rats received no treatment for 8 wks. In a molar cusp-less (OD) group, maxillary molar cusps were cut off with a dental turbine at baseline and kept for 8 wks. In a molar cusp-less + recovered cusp (OR) group, maxillary molar cusps were cut off and then were recovered after 4 wks using resin material. After the experimental period, expression of BDNF mRNA and protein as well as histological findings were evaluated in the submandibular glands. The comparisons between the groups were made using the Mann-Whitney U test with Bonferroni correction.


RESULTS
the OD group showed a significant increase in submandibular gland BDNF mRNA and protein expression after 8 wks, and plasma adrenocorticotropic hormone and corticosterone levels increased in a time-dependent manner. There were no significant differences in BDNF expression in the submandibular glands and in levels of plasma adrenocorticotropic hormone and corticosterone between the OR and C groups.


CONCLUSIONS
these results indicate that psychological stress induced by occlusal disharmony reversibly induces BDNF expression in the rat submandibular gland.
Irie
Koichiro
K
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.
Ekuni
Daisuke
D
Tomofuji
Takaaki
T
Azuma
Tetsuji
T
Endo
Yasumasa
Y
Kasuyama
Kenta
K
Morita
Manabu
M
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000032:analysis / Q000096:biosynthesis* / Q000097:blood; D003345:Corticosterone / Q000097:blood; D003442:Crowns; D008297:Male; D008310:Malocclusion / Q000378:metabolism*; D008963:Molar / Q000503:physiopathology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D018987:Salivary Ducts / Q000378:metabolism / Q000473:pathology; D012471:Salivary Proteins and Peptides / Q000032:analysis / Q000378:metabolism; D013315:Stress, Psychological / Q000378:metabolism; D013363:Submandibular Gland / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors
D019208:Brain-Derived Neurotrophic Factor; D012471:Salivary Proteins and Peptides; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone