Korean J Anat.  2006 Aug;39(4):297-303.

The Ultrastructure of TRPV1-positive Nerve Terminals in the Human Tooth Pulp

Affiliations
  • 1Department of Conservative Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea
  • 2Department of Oral Anatomy, School of Dentistry, Kyungpook National University, Daegu, Korea. ycbae@knu.ac.kr

Abstract

The vanilloid receptor TRPV1 has been suggested to play an important role in thermal nociception and inflammatory hyperalgesia. In our previous study, we examined the expression of TRPV1 and colocalization of TRPV1 with substance P (SP) and calcitonin gene related peptide (CGRP) through fluorescence immunocytochemistry. Here, we investigated ultrastructural characteristics of TRPV1 immunoreactive fibers in the human tooth pulp through preembedding immunocytochemistry. TRPV1 immunoreactivity was present in the unmyelinated nerve fibers in the tooth pulp. There were two types of TRPV1 IR nerve fibers identified in the human tooth pulp: one containing clear round vesicles and many dense-cored vesicles, the other containing clear round vesicles and few dense-cored vesicles. TRPV1 immunoreactive fibers were constant in diameter without swellings along the length. Boutons en passant and boutons terminaux usually observed in the CNS were not observed in the TRPV1 immunoreactive fibers. Many vesicles were accumulated in the TRPV1 immunoreactive fibers, however synaptic structure was not found. It is known that dense-cored vesicles contain neuropeptides such as SP and CGRP and clear round vesicles contain neurotransmitter such as glutamate. Taken together, our results suggest that TRPV1 immunoreactive fibers showing distinct ultrastructructural features may be involved in inflammatory hyperalgesia and thermal nociception in the tooth pulp.

Keyword

TRPV1 immunoreactive fibers; Ultrastructural characteristics; Clear round vesicles; Dense-cored vesicles; Inflammatory hyperalgesia; Thermal nociception

MeSH Terms

Calcitonin Gene-Related Peptide
Fluorescence
Glutamic Acid
Humans*
Hyperalgesia
Immunohistochemistry
Nerve Fibers
Nerve Fibers, Unmyelinated
Neuropeptides
Neurotransmitter Agents
Nociception
Substance P
Tooth*
Calcitonin Gene-Related Peptide
Glutamic Acid
Neuropeptides
Neurotransmitter Agents
Substance P
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