Immunohistochemical demonstration of neuropeptides in the articular disk of the human temporomandibular joint

The distribution of calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal polypeptide (VIP) a nd neuropeptide Y (NPY) was examined in the human temporomandibular articular disk using an indirect immunofluorescent method. All examined neuropeptides were observed in nerve fibers in the disk. These fibers were mostly located in the loose fibrous tissue of the posterior part (posterior attachment) and in the lateral region of the anterior part (anterolateral loose fibrous tissue) of the disk. The posterior attachment and anterolateral loose fibrous tissue occasionally contained isolated nerve fibers which usually showed immunoreactivity (IR) for CGRP or SP. In this tissue, perivascular fibers contained VIP or NPY, whereas isolated fibers and free nerve endings showed the IR for CG RP or SP. These neuropeptides may be involved in the regulation of blood flow and/or pain sensation in the human articular disk of the temporomandibular joint.