Vesicular Glutamate Transporter Immunoreactivity in the Periodontal Ligament of the Rat Incisor

Authors

  • Shiho Honma,

    Corresponding author
    1. Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan
    2. Center for Frontier Oral Science, Osaka University Graduate School of Dentistry, Osaka, Japan
    • Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, 1–8 Yamadaoka, Suita, Osaka 565-0871, Japan
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    • Fax: +81-6-6879-2875

  • Akiko Kato,

    1. Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan
    2. Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan
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  • Lei Shi,

    1. Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan
    Current affiliation:
    1. Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, People's Republic of China.
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  • Hirofumi Yatani,

    1. Center for Frontier Oral Science, Osaka University Graduate School of Dentistry, Osaka, Japan
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  • Satoshi Wakisaka

    1. Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka, Japan
    2. Center for Frontier Oral Science, Osaka University Graduate School of Dentistry, Osaka, Japan
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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. Anat Rec, 2012. © 2011 Wiley Periodicals, Inc.

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