Expression of the TRPM8-immunoreactivity in dorsal root ganglion neurons innervating the rat urinary bladder

• Published in: Neuroscience research Vol. 65; no. 3; pp. 245 - 251
• Main Authors: Hayashi, Tokumasa, Kondo, Teruyoshi, Ishimatsu, Masaru, Yamada, Satoko, Nakamura, Kei-ichiro, Matsuoka, Kei, Akasu, Takashi
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01-11-2009
• Subjects: Animals; Biomarkers - metabolism; Calcitonin Gene-Related Peptide - metabolism; Cell Count; CGRP; Dorsal root ganglion; Female; Ganglia, Spinal - cytology; Ganglia, Spinal - metabolism; IB4; Immunohistochemistry; Nerve Fibers, Myelinated - metabolism; Nerve Fibers, Myelinated - ultrastructure; Nerve Fibers, Unmyelinated - metabolism; Nerve Fibers, Unmyelinated - ultrastructure; Neuroanatomical Tract-Tracing Techniques - methods; Neurofilament Proteins - metabolism; NF200; Nociceptors - cytology; Nociceptors - metabolism; Pain - metabolism; Pain - physiopathology; Plant Lectins; Rat; Rats; Rats, Wistar; Sensory Receptor Cells - cytology; Sensory Receptor Cells - metabolism; TRPM Cation Channels - metabolism; TRPM8; TRPV Cation Channels - metabolism; TRPV1; Urinary bladder; Urinary Bladder - innervation; Visceral Afferents - cytology; Visceral Afferents - metabolism; Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; NF200; Urinary bladder; Rat; IB4; TRPM8; TRPV1; Dorsal root ganglion; CGRP
• ISSN: 0168-0102; 1872-8111
• DOI: 10.1016/j.neures.2009.07.005

The neurochemical phenotypes of the transient receptor potential melastatin-8 (TRPM8)-immunoreactive afferent neurons innervating the rat urinary bladder were examined by using a highly sensitive tyramide signal amplification method, combined with wheat-germ agglutinin-horseradish peroxidase (WGA-HRP) retrograde tracing. TRPM8-immunoreactivity was detected in a small proportion of the WGA-HRP-labeled bladder afferent neurons in the dorsal root ganglia of the Th13-L1 (1.14%) and the L6-S1 (1.27%), and these neurons were small in size (<600
μm
2). The 82.6
±
3.8% of the TRPM8-immunoreactive bladder afferent neurons and 80.9
±
1.5% of the total population of the TRPM8-immunoreactive afferent neurons in the observed dorsal root ganglia expressed NF200. On the other hand, the proportions of the co-expression of TRPM8 and nociceptive markers such as calcitonin gene-related peptide (CGRP), transient receptor potential vanilloid-1 (TRPV1), and isolectin B4 (IB4) in the bladder afferent neurons (81.5
±
5.2% for CGRP, 36.1
±
4.0% for TRPV1, and 15.8
±
5.5% for IB4) were
higher in comparison to those in the total population of the TRPM8-immunoreactive afferent neurons (21.9
±
2.4% for CGRP, 16.6
±
1.7% for TRPV1, and 5.4
±
0.5% for IB4), although no significant difference existed for IB4. Our results suggest that the TRPM8-expressing bladder afferents should be classified as Aδ-fibers and C-fibers, while some of these afferents may be involved in nociceptive sensations.