Expression of metabotropic glutamate receptor mGluR5 in human dental pulp.
Accumulating evidence indicates that the metabotropic glutamate receptor mGluR5 is involved in the peripheral mechanisms of inflammatory nociception. To investigate whether mGluR5 may mediate the inflammatory pain and thermal hyperalgesia in the dental pulp, we examined the expression of mGluR5 and transient receptor potential vanilloid 1 (TRPV1) in human dental pulp by immunohistochemistry and electron microscopy; mGluR5-immunopositive (+) axons were observed in nerve bundles and branched extensively within the peripheral coronal pulp. Most of the mGluR5+ axons were unmyelinated. A large fraction of these axons (36.5%) were immunostained for TRPV1. Immunoreactivity for mGluR5 and TRPV1 was also observed in odontoblasts. These results support the possibility that the nerve fibers in the dental pulp mediate inflammatory pain and thermal hyperalgesia through coactivation of mGluR5 and TRPV1 and also suggest a possible role for odontoblasts in the transduction of nociceptive signals via mGluR5-mediated mechanism.
Kim
Yun Sook
YS
Department of Oral Anatomy and Neurobiology, BK21, School of Dentistry, Kyungpook National University, Daegu, Korea.
Kim
Young Jae
YJ
Paik
Sang Kyoo
SK
Cho
Yi Sul
YS
Kwon
Tae Geon
TG
Ahn
Dong Kuk
DK
Kim
Sung Kyo
SK
Yoshida
Atsushi
A
Bae
Yong Chul
YC
D000293:Adolescent; D001369:Axons / Q000473:pathology; D003782:Dental Pulp / Q000294:innervation / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D006930:Hyperalgesia / Q000473:pathology; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D036421:Nerve Fibers, Unmyelinated / Q000473:pathology; D009804:Odontoblasts / Q000473:pathology; D010146:Pain / Q000473:pathology; D011671:Pulpitis / Q000473:pathology; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000032:analysis*; D015398:Signal Transduction / Q000502:physiology; D050916:TRPV Cation Channels / Q000032:analysis; D013696:Temperature; D055815:Young Adult
C578935:GRM5 protein, human; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human