Distribution of Vanilloid Receptor VR1 in the Human Dental Pulp

Objectives: Vanilloid receptor VR1 is involved in thermal nociception and inflammatory hyperalgesia and is also essential for the development and maintenance of thermal hyperalgesia and allodynia, which are associated with inflammation and tissue injury. The aim of the study was to investigate the distribution of vanilloid receptor VR1 in the human dental pulp. Methods: Thirteen human sound first or second premolar teeth were used immediately after extraction for orthodontic reason. After specimen preparation, pulp tissue was treated with antibodies of VR1 (Santa Cruz Biotechnology, USA). Image was analyzed to quantify the localization of VR1. VR1 immunoreactivity in fibers was examined and quantified by computerized image analysis (i-solution, iMTechnology, Daejeon, Korea). Counts of VR1 immunopositive fibers were taken from the random fields (100 x 100 µm2 in each field) of three areas (peripheral coronal, central coronal and radicular area) in each section. Results were expressed as a percentage of VR1-positive fibers to pulpal nerve fibers. Statistical comparisons of three different area were done by Chi-squared test (SAS 8.02, p<0.05) Results: Numerous nerve fibers in the human dental pulp were stained for VR1. The staining was intense and was evenly distributed. VR1 immunoreactivity was shown in thin varicose nerves in subodontoblastic plexus as well. VR1 immunoreactive nerve fibers in coronal center traveled with blood vessel. Its immunoreactivity was also seen in nerve bundles in central coronal and radicular pulp. There was no significant differences in the ratio of VR1 immunoreactive nerve fibers among the three different area (p>0.05). Conclusion: This study demonstrates that numerous VR1 immunoreactive nerve fibers exist in the human dental pulp. VR1 immunoreactive nerve fiber were evenly distributed among the three different areas in dental pulp in terms of percentage of VR1-positive fibers to pulpal nerve fibers.