title: Expression of GDNF and its receptors in the periodontal mechanoreceptor.
abstract: Our previous studies have revealed the involvement of signaling pathways of BDNF and NT-4/5 via TrkB in the development, regeneration, survival and maintenance of the Ruffini endings, primary mechanoreceptors in the periodontal ligament. However, the involvement of other neurotrophins remains unclear. The present study examined the expression of GDNF, GFRalpha1, and RET in the incisor periodontal ligament and trigeminal ganglion of young rats by RT-PCR and immunocytochemistry. All these mRNAs were detected in both tissues by RT-PCR. These immunoreactions were found in the terminal Schwann cells associated with the periodontal Ruffini endings, as confirmed by histochemistry for non-specific cholinesterase activity. Their axonal branches showed GFRalpha1- and RET-immunoreactions but lacked GDNF-immunoreactivity. In the trigeminal ganglion, about 30% of the neurons were immunoreactive to GFRalpha1 and RET. Averages of cross-sectional areas of their positive neurons demonstrated that they could mainly be categorized as medium-sized neurons. GDNF-immunoreaction was restricted to the satellite cells and not in trigeminal ganglion neurons. These findings indicate that GDNF mediates trophic effects on the survival and target innervation of the periodontal Ruffini endings via GFRalpha1 and RET.
authors.affiliation: Division of Oral Anatomy, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. aitam@dent.niigata-u.ac.jp
authors.forename: Megumi
authors.initials: M
authors.lastname: Aita
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Kawano
authors.forename: Takeyasu
authors.initials: T
authors.lastname: Maeda
mesh_terms: D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008465:Mechanoreceptors / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020813:Receptor, trkB / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D043222:Ubiquitin Thiolesterase / Q000378:metabolism; D000070584:Tripartite Motif Proteins
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D020813:Receptor, trkB; D043222:Ubiquitin Thiolesterase; C489295:Trim27 protein, rat; D000070584:Tripartite Motif Proteins; C482860:UCHL1 protein, human