VR1-, VRL-1- and P2X3 receptor-immunoreactive innervation of the rat temporomandibular joint

• Published in: Brain research Vol. 1008; no. 1; pp. 131 - 136
• Main Authors: Ichikawa, H., Fukunaga, T., Jin, H.W., Fujita, M., Takano-Yamamoto, T., Sugimoto, T.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 15-05-2004; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Biological and medical sciences; Calcitonin Gene-Related Peptide - metabolism; Cell Count - methods; Cell Size - physiology; Fluorescent Dyes - metabolism; Fundamental and applied biological sciences. Psychology; Immunohistochemistry; Immunohistochemistry - methods; Ion Channels; Male; Nerve Fibers - metabolism; P2X3; Rats; Rats, Sprague-Dawley; Receptors, Drug - metabolism; Receptors, Purinergic P2 - metabolism; Receptors, Purinergic P2X3; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Stilbamidines - metabolism; Temporomandibular joint; Temporomandibular Joint - innervation; Temporomandibular Joint - metabolism; Trigeminal ganglion; TRPV Cation Channels; Vertebrates: nervous system and sense organs; VR1; VRL-1; Immunohistochemistry; VR1; VRL-1; Sensory systems; P2X3; Temporomandibular joint; Trigeminal ganglion; P2X3 purinergic receptor; Rat; Innervation; Rodentia; Trigcminal ganglion; Vertebrata; VR1 vanilloid receptor; Mammalia
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2004.02.029

Immunohistochemistry for vanilloid receptor subtype 1 (VR1), vanilloid receptor 1-like receptor (VRL-1) and P2X3 receptor was performed in the rat temporomandibular joint (TMJ). Blood vessels in the articular disk and capsule, the synovial membrane and the fibrous tissue around the condylar process were innervated by VR1- or P2X3 receptor-immunoreactive (ir) nerve fibers. However, VRL-1-immunoreactivity (ir) could not be detected in the TMJ. Retrograde tracing and immunohistochemical methods revealed that 25%, 41% and 52% of TMJ neurons in the trigeminal ganglion (TG) exhibited VR1-, VRL-1- and P2X3 receptor-ir, respectively. VR1-ir TMJ neurons were mostly small to medium-sized, whereas VRL-1- and P2X3 receptor-ir TMJ neurons were predominantly medium-sized to large. In addition, 73%, 28% and 44% of VR1-, VRL-1- and P2X3 receptor-ir TMJ neurons, respectively, coexpressed calcitonin gene-related peptide (CGRP)-ir. The present study suggests that the TMJ has abundant nociceptors which respond to vanilloid compounds, protons, heat and extracellular ATP.