title: Sympathetic Regulation of Tertiary Dentinogenesis via Beta-2 Adrenergic Receptor on Rat Odontoblasts.
abstract: BACKGROUND
  Beta-2 adrenergic receptor has been found within the osteoblast membrane meditating bone remodeling. Propranolol is a sympatholytic beta antagonist commonly used as long-term medication for the management of many common diseases such as hypertension. This study was performed to verify the presence of this receptor on odontoblasts in rats and, if present, to investigate its possible association with tertiary dentinogenesis.
  
  
  METHODS
  Twenty male Sprague-Dawley rats (9 weeks old) were randomly assigned to 4 groups: CP0.8 group, cavity preparation + propranolol treatment (0.8 mg/day, n = 5); CP4 group, cavity preparation + propranolol treatment (4.0 mg/day, n = 7); CON group, cavity preparation + saline treatment (0.2 mL/day, n = 5); and NT group, no treatment (n = 3). Cavity preparation was performed on the mesial aspect of the maxillary first molars bilaterally. After 2 weeks, the tertiary dentinogenesis (CP0.8, CP4, and CON) was examined by hematoxylin-eosin staining, and the localization of beta-2 adrenergic receptor (NT) was examined by immunohistochemistry.
  
  
  RESULTS
  The beta-2 adrenergic receptor immunoreactivity was observed in the odontoblastic layer in normal rat molar dental pulp. The tertiary dentinogenesis beneath the prepared cavity was significantly higher in the rats receiving 2-week systemic administration of propranolol than in those without the propranolol treatment. The higher-dose treatment of propranolol (P < .001) presented more effective up-regulation of tertiary dentinogenesis than the lower-dose treatment (P < .01).
  
  
  CONCLUSIONS
  These results indicate that the sympathetic nervous system decreases tertiary dentin formation via beta-2 adrenergic receptors located on rat odontoblasts. It suggests that adrenergic beta antagonist is expected to use in the treatment of inducing tertiary dentin formation to protect dental pulp.
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Jie
authors.initials: J
authors.lastname: Gu
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan. Electronic address: hms-ikeda.endo@tmd.ac.jp.
authors.forename: Hideharu
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Suda
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D003810:Dentinogenesis / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009804:Odontoblasts / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D000319:Adrenergic beta-Antagonists; D018343:Receptors, Adrenergic, beta-2; D011433:Propranolol
keywords: Beta-2 adrenergic receptor; indirect pulp capping; odontoblast(s); propranolol; sympathetic nervous system; tertiary dentinogenesis