Ultrastructure of Substance P Immunopositive Axons in the Human Dental Pulp
10.11620/IJOB.2018.43.3.155
- Author:
Byung Hee MOON
1
;
Jung Hong HA
;
Hye Min HAN
;
Tae Heon KIM
;
Sook Kyung PARK
;
Yong Chul BAE
Author Information
1. Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea. ycbae@knu.ac.kr
- Publication Type:Original Article
- Keywords:
dental pulp;
substance P;
nerve fiber;
ultrastructure;
immunohistochemistry
- MeSH:
Axons;
Dental Pulp;
Glutamic Acid;
Humans;
Immunohistochemistry;
Microscopy;
Microscopy, Electron;
Mitochondria;
Nerve Fibers;
Spinal Cord;
Substance P
- From:International Journal of Oral Biology
2018;43(3):155-160
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
There exists very little information on the ultrastructure of substance P immunopositive (+) fibers in the human dental pulp, which may help in understanding the mechanism for substance P associated pulpal inflammatory pain. To address this issue, we investigated the presence of substance P+ fibers in the human dental pulp by light- and electron-microscopic immunohistochemistry. Light microscopy revealed that substance P+ fibers ran within neurovascular bundles in the radicular pulp and in the core of coronal pulp. They were also frequently present in the peripheral pulp. Substance P+ fibers showed beads like swellings interconnected by thin axonal strand, in a manner similar to bouton en passants and interconnecting axonal strand in the spinal cord. Electron microscopy revealed that almost all the substance P+ axons were unmyelinated. The axonal swellings of the substance P+ contained numerous clear round vesicles (40–50 nm in diameter) and many large dense-cored vesicles (80–110 nm in diameter) as well as many mitochondria. The vesicles and mitochondria were rarely observed in the thin axonal strand interconnecting the swellings. Intimate interrelationship or synaptic structure between the swellings of substance P+ axon and nearby pulpal cells or axons was not found. These findings suggest co-release of substance P and glutamate from the substance P+ pulpal axons and its action on nearby structures in a paracrine manner.
