title: Salivary glands as the source of plasma brain-derived neurotrophic factor in stressed rats engaged in biting behavior.
abstract: Brain-derived neurotrophic factor (BDNF) is crucial for the survival and differentiation of the central and peripheral nervous systems. Recently, BDNF has been reported to exert broader biological activity on non-neural cells. A previous study examined the effect of immobilization stress on BDNF and its receptor tyrosine receptor kinase B in male rat submandibular glands. In the present study, we found that the rat submandibular gland is the major source of plasma BDNF during acute immobilization stress. Biting modulates the mRNA and protein levels of BDNF in the rat hippocampus, so we also investigated whether the plasma BDNF concentration is influenced by biting. Two hours of acute immobilization stress significantly increased the amount of BDNF mRNA within the rat submandibular glands. Moreover, allowing biting behavior for the second half of the 2-h stress exposure significantly increased the amount of salivary gland BDNF mRNA relative to stress alone. Similar results were found with plasma BDNF concentrations under the same conditions. We confirmed that biting during stress attenuates the increases in plasma adrenocorticotropic hormone and corticosterone concentrations, but this was not dependent on the submandibular glands. Increased BDNF, mRNA and protein expressions were observed in salivary duct cells as a result of immobilization stress and biting behavior, as demonstrated by real-time polymerase chain reaction, immunohistochemistry, western blotting, and enzyme-linked immunosorbent assay. Taken together, the findings indicate that the submandibular glands evidently contribute to the increase in plasma BDNF upon biting.
authors.affiliation: Department of Craniofacial Growth and Development Dentistry, Division of Orthodontics, Kanagawa Dental College, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Juri
authors.initials: J
authors.lastname: Saruta
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kondo
authors.forename: Chikatoshi
authors.initials: C
authors.lastname: Sato
authors.forename: Naoto
authors.initials: N
authors.lastname: Shiiki
authors.forename: Keiichi
authors.initials: K
authors.lastname: Tsukinoki
authors.forename: Sadao
authors.initials: S
authors.lastname: Sato
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000374:Aggression / Q000502:physiology; D000818:Animals; D001733:Bites and Stings / Q000378:metabolism* / Q000503:physiopathology; D019208:Brain-Derived Neurotrophic Factor / Q000097:blood* / Q000235:genetics*; D003345:Corticosterone / Q000097:blood; D007150:Immunohistochemistry; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013312:Stress, Physiological / Q000502:physiology*; D013363:Submandibular Gland / Q000502:physiology*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone