Neurochemical Characterization of the TRPV1-Positive Nociceptive Primary Afferents Innervating Skeletal Muscles in the Rats.
10.3340/jkns.2008.43.2.97
- Author:
Dong Su SHIN
1
;
Eun Hyun KIM
;
Kwan Young SONG
;
Hyun Jong HONG
;
Min Ho KONG
;
Se Jin HWANG
Author Information
1. Department of Neurosurgery, Seoul Medical Center, Seoul, Korea.
- Publication Type:Original Article
- Keywords:
Skeletal muscle;
Pain;
Primary afferents;
TRPV1;
CGRP;
Dorsal root ganglion
- MeSH:
Acetates;
Acetic Acid;
Amidines;
Animals;
Calcitonin Gene-Related Peptide;
Fluorescent Antibody Technique;
Ganglia, Spinal;
Muscle, Skeletal;
Muscles;
Neurons;
Nociception;
Phosphotransferases;
Rats;
Rats, Sprague-Dawley;
Skin;
Spinal Cord;
Viscera
- From:Journal of Korean Neurosurgical Society
2008;43(2):97-104
- CountryRepublic of Korea
- Language:English
-
Abstract:
OBJECTIVE: Transient receptor potential vanilloid subfamily type 1 (TRPV1), a most specific marker of the nociceptive primary afferent, is expressed in peptidergic and non-pepetidergic primary afferents innervating skin and viscera. However, its expression in sensory fibers to skeletal muscle is not well known. In this study, we studied the neurochemical characteristics of TRPV1-positive primary afferents to skeletal muscles. METHODS: Sprague-Dawley rats were injected with total 20 microliter of 1% fast blue (FB) into the gastrocnemius and erector spinae muscle and animals were perfused 4 days after injection. FB-positive cells were traced in the L4-L5 (for gastrocnemius muscle) and L2-L4 (for erector spinae muscle) dorsal root ganglia. The neurochemical characteristics of the muscle afferents were studied with multiple immunofluorescence with TRPV1, calcitonin gene-related peptide (CGRP) and P2X(3). To identify spinal neurons responding to noxious stimulus to the skeletal muscle, 10% acetic acids were injected into the gastrocnemius and erector spinae muscles and expression of phospho extracellular signal-regulated kinase (pERK) in spinal cords were identified with immunohistochemical method. RESULTS: TRPV1 was expressed in about 49% of muscle afferents traced from gastrocnemius and 40% of erector spinae. Sixty-five to 60% of TRPV1-positive muscles afferents also expressed CGRP. In contrast, expression of P2X3 immnoreaction in TRPV1-positive muscle afferents were about 20%. TRPV1-positive primary afferents were contacted with spinal neurons expressing pERK after injection of acetic acid into the muscles. CONCLUSION: It is consequently suggested that nociception from skeletal muscles are mediated by TRPV1-positive primary afferents and majority of them are also peptidergic.
