Korean J Anesthesiol.  2014 Mar;66(3):230-236. 10.4097/kjae.2014.66.3.230.

G protein-coupled receptor, family C, group 5 (GPRC5B) downregulation in spinal cord neurons is involved in neuropathic pain

• Chung HJ
• Kim JD
• Kim KH
• Jeong NY

• KMID: 2092450
• DOI: http://doi.org/10.4097/kjae.2014.66.3.230

Abstract

BACKGROUND
G protein-coupled receptor, family C, group 5 (GPRC5B), a retinoic acid-inducible orphan G-protein-coupled receptor (GPCR), is a member of the group C metabotropic glutamate receptor family proteins presumably related in non-canonical Wnt signaling. In this study, we investigated altered GPRC5B expression in the dorsal horn of the spinal cord after spinal nerve injury and its involvement in the development of neuropathic pain.
METHODS
After induction of anesthesia by intraperitoneal injection of pentobarbital (35 mg /kg), the left L5 spinal nerve at the level of 2 mm distal to the L5 DRG was tightly ligated with silk and cut just distal to the ligature. Seven days after nerve injury, animals were perfused with 4% paraformaldehyde, and the spinal cords were extracted and post-fixed at 4degrees C overnight. To identify the expression of GPRC5B and analyze the involvement of GPRC5B in neuropathic pain, immunofluorescence was performed using several markers for neurons and glial cells in spinal cord tissue.
RESULTS
After L5 spinal nerve ligation (SNL), the expression of GPRC5B was decreased in the ipsilateral part, as compared to the contralateral part, of the spinal dorsal horn. SNL induced the downregulation of GPRC5B in NeuN-positive neurons in the spinal dorsal horn. However, CNPase-positive oligodendrocytes, OX42-positive microglia, and GFAP-positive astrocytes were not immunolabeled with GPRC5B antibody in the spinal dorsal horn.
CONCLUSIONS
These results imply that L5 SNL-induced GPRC5B downregulation may affect microglial activation in the spinal dorsal horn and be involved in neuropathic pain.

Keyword

GPCR5B; Microglial activation; Neuroglial cell; Neuropathic pain; Spinal nerve injury

MeSH Terms

Anesthesia
Animals
Astrocytes
Child
Child, Orphaned
Diagnosis-Related Groups
Down-Regulation*
Fluorescent Antibody Technique
Horns
Humans
Injections, Intraperitoneal
Ligation
Microglia
Neuralgia*
Neuroglia
Neurons*
Oligodendroglia
Pentobarbital
Receptors, Metabotropic Glutamate
Silk
Spinal Cord*
Spinal Nerves
Pentobarbital
Receptors, Metabotropic Glutamate
Silk