Topography and distribution of sympathetic nerve fibers in the rat temporomandibular joint: immunocytochemistry and ultrastructure

Abstract

The distribution and fine structure of nerve fibers containing neuropeptide Y (NPY), tyrosine hydroxylase (TH), and vasoactive intestinal polypeptide (VIP) in the temporomandibular joint were investigated by both the avidin-biotin complex method and an indirect immunofluorescence technique. The innervation pattern of NPY- and TH-positive fibers differed from that of VIP-positive fibers. Specifically, the former was distributed in both the superficial and deep sublining layers, while the latter was mostly located in the deep sublining layer. NPY- and TH-immunoreactive fibers were largely confined to vascular elements; occasional fibers were observed in the synovial lining layer close to the joint cavity. More nerves with NPY and TH immunoreactivity were observed close to the upper joint compartment than near the lower compartment NPY and TH immunoreactivity was dramatically reduced in the TMJ of superior cervical ganglionectomized animals, indicating the sympathetic origin of these nerves. NPY immunoreactivity was found only in unmyelinated axons, which were located in the adventitia and adventitia-medial border of arteries or arterioles. Occasionally, axons were near the joint cavity, in areas free of vascular structures. These observations show that abundant sympathetic nerves supply the temporomandibular joint of the rat and provide a morphological basis for the involvement of different neuropeptides in vascular regulatory and modulatory functions in physiological and pathophysiological conditions.

Capsaicin receptor expression in the rat temporomandibular joint

“…Some nerves only exhibit PGP 9.5 labeling (red arrows). Bars 50 μm not with TRPV1 seemed to be sympathetic in origin, as demonstrated previously (Kido et al 2001).…”

Phenotypic alterations of neuropeptide Y and calcitonin gene-related peptide-containing neurons innervating the rat temporomandibular joint during carrageenan-induced arthritis

“…17–21 Axons innervating the TMJ contain several neuropeptides, among which are the NPY and the CGRP. 22–26 NPY is a 36 amino acid sequence related to the pancreatic polypeptide family. It is synthesized in the rat peripheral nervous system, mainly by autonomic sympathetic and parasympathetic neurons.…”

Distribuição dos neurônios e campos terminais que expressam a urocortina 3 no sistema nervoso central de primata não-humano (Cebus apella).

“…3). Kido et al (2001) had also observed a dense NPY innervation in the rat TMJ originating from superior cervical ganglion. Since a similar approach has not been made in any other joint, comparisons were made with previous studies involving the innervation of other orofacial territories.…”

“…However, very little is known about the possible functions of parasympathetic innervation in the TMJ. In a previous study, it was observed that the removal of the rat superior cervical ganglion resulted in the complete absence of NPY fibers in the TMJ 10 .…”

“…Axons innervating the TMJ contain several neuropeptides, among them are the neuropeptide Y (NPY) and the calcitonin gene related peptide (CGRP) 6,7,8,9,10 . NPY is a 36 amino acid sequence related to the pancreatic polypeptide family.…”