Nerve terminals extend into the temporomandibular joint of adjuvant arthritic rats.
The innervation of the temporomandibular joint (TMJ) has attracted particular interest because of the close association with complex mandibular movement. Although the pathological changes of disk innervation may have a crucial role in the development of TMJ pain, the innervation of the TMJ disk by experimentally induced arthritis has rarely been examined in detail. Arthritic rats were induced by injection with 0.1ml solution of Complete Freund's adjuvant (CFA). We investigated three-dimensional distribution of nerve fibers in the TMJ disk using immunohistochemistry for protein gene product-9.5 (PGP-9.5) and calcitonin gene-related peptide (CGRP) in naive and arthritic rats. To clarify the possible role of nerve growth factor (NGF) and its receptor on changes in peripheral innervation of the TMJ, the expressions of trkA and p75 receptor in trigeminal ganglia were examined. Although PGP-9.5 and CGRP immunoreactive (ir) fibers were seen in the peripheral part of the TMJ disk, they were not seen in its central part. The total length and the length density of PGP-9.5 ir and CGRP ir nerve fibers increased in arthritic rats. The innervation area of fibers proliferating in the rostro-medial part merged with that of fibers in the rostro-lateral part in the arthritic rats. In addition, the ratio of trkA- and p75-positive small- and medium-sized cells increased in trigeminal ganglia. It is assumed that increasing innervation of the TMJ disk may be important for the pathophysiology of TMJ pain. NGF and its receptors are likely involved in pathological changes of the TMJ disk.
Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Masamichi
M
Shinoda
Takashi
T
Honda
Noriyuki
N
Ozaki
Hisashi
H
Hattori
Hideki
H
Mizutani
Minoru
M
Ueda
Yasuo
Y
Sugiura
D000818:Animals; D001168:Arthritis / Q000139:chemically induced / Q000378:metabolism*; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D005620:Freund's Adjuvant; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D009412:Nerve Fibers / Q000737:chemistry / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000378:metabolism; D010146:Pain / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism; D013704:Temporomandibular Joint / Q000294:innervation* / Q000378:metabolism; D012668:Trigeminal Ganglion / Q000378:metabolism
D002352:Carrier Proteins; D008565:Membrane Proteins; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D005620:Freund's Adjuvant; D020932:Nerve Growth Factor; D020917:Receptor, trkA; D015740:Calcitonin Gene-Related Peptide