title: Vesicular glutamate transporter immunoreactivity in the periodontal ligament of the rat incisor.
abstract: The distribution of three vesicular glutamate transporter (VGluT) isoforms, VGluT1, VGluT2, and VGluT3, were investigated in the trigeminal ganglion of the periodontal ligament in the rat incisor-a receptive field of trigeminal ganglion neurons. In the trigeminal ganglion, mRNAs for all VGluT isoforms were detected and proteins were observed in the cytoplasm of trigeminal ganglion cells. VGluT1 immunoreactions were localized within the cytoplasm for all sizes of trigeminal neurons, although predominately in medium-large trigeminal neurons. Double-labeling showed that most VGluT1 contained both VGluT2 and VGluT3. In the periodontal ligament of the incisor, the Ruffini endings, principal periodontal mechanoreceptors, displayed VGluT1 and VGluT2 immunoreactivities. However, lacked immunoreactions for VGluT3. At the electron microscopic level, VGluT1 immunoreactions were localized around the vesicle membranes at the axon terminal of Ruffini endings. The present results indicate that VGluT is expressed in the sensory nerve endings where apparent synapses are not present. Thus, glutamate in the sensory nerve endings is thought to be used in metabotropic functions. This is because glutamate is a general metabolic substrate, and/or acts as a neurotransmitter as proposed in muscle spindles.
authors.affiliation: Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Japan. honma@dent.osaka-u.ac.jp
authors.forename: Shiho
authors.initials: S
authors.lastname: Honma
authors.forename: Akiko
authors.initials: A
authors.lastname: Kato
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yatani
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakisaka
mesh_terms: D000818:Animals; D007150:Immunohistochemistry; D007180:Incisor / Q000294:innervation*; D008297:Male; D008465:Mechanoreceptors / Q000378:metabolism / Q000648:ultrastructure; D010513:Periodontal Ligament / Q000294:innervation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000378:metabolism* / Q000648:ultrastructure; D012668:Trigeminal Ganglion / Q000166:cytology / Q000378:metabolism*; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism*; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism*; D050496:Vesicular Glutamate Transport Proteins / Q000378:metabolism*
chemical_list: C493475:Slc17a6 protein, rat; C493466:Slc17a7 protein, rat; C482103:Slc17a8 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D050496:Vesicular Glutamate Transport Proteins