Endothelin receptors and endothelin-1 in developing rat teeth.
BACKGROUND
The endothelins are a family of small peptides with multiple roles in a variety of tissues. Signaling is mediated through two receptor subtypes, the endothelin A receptor (ET(A)) specific for Et-1 and the non-specific endothelin B receptor (ET(B)).


OBJECTIVE
Our goal was to determine the location of immunoreactivity (IR) for ET(A) and ET(B) in developing and mature rat teeth as indicators of endothelin (Et) regulatory sites and to compare this to the Et-1 (ligand)-IR expression patterns.


METHODS
We used immunohistochemistry to study developing and mature rat molars and continuously developing incisors.


RESULTS
We demonstrate ET(A), ET(B), and Et-1 expression patterns in teeth, for the first time. ET(A) was found in developing molar root pulp, pulpal vasculature, and preodontoblasts, and then persisted in odontoblasts or cellular cementocytes at the root apices of mature teeth. ET(B) was found at the molar (Hertwig's) root sheath during root formation and in molar ameloblasts, nerve fibers and odontoblasts of immature and mature teeth. In incisors, ET(B)-IR was associated with ameloblasts and the stem cell niche of the cervical loop while ET(A) was located in the substratum layer. Et-1 was found throughout the dental and periodontal tissues with higher concentrations associated with odontoblasts, nerves and incisor layers that expressed ET(B).


CONCLUSIONS
The patterns of ET(A) and ET(B) in teeth differ from each other and from those of adjacent tissues suggesting multiple tooth-specific functions for endothelin during development and mature dental function.
Neuhaus
Scott J
SJ
Department of Restorative Dentistry, University of Washington, Seattle, WA 98195, USA. sjn007@u.washington.edu
Byers
Margaret R
MR
D000565:Ameloblasts / Q000166:cytology; D000818:Animals; D003739:Dental Cementum / Q000166:cytology; D003782:Dental Pulp / Q000098:blood supply / Q000166:cytology; D019332:Endothelin-1 / Q000032:analysis*; D007150:Immunohistochemistry; D007180:Incisor / Q000166:cytology; D008024:Ligands; D008297:Male; D008963:Molar / Q000166:cytology; D009804:Odontoblasts / Q000166:cytology; D009805:Odontogenesis / Q000502:physiology*; D010519:Periodontium / Q000166:cytology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A / Q000032:analysis*; D044023:Receptor, Endothelin B / Q000032:analysis*; D013234:Stem Cells / Q000166:cytology; D014070:Tooth / Q000166:cytology*; D014092:Tooth Root / Q000166:cytology
D019332:Endothelin-1; D008024:Ligands; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B