Origin, Distribution and Fine structure of the Sympathetic nerves in the rat TMJ.

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The distribution of nerve fibers containing neuropeptide Y (NPY), tyrosine hydroxylase (TH) and vasoactive intestinal polypeptide (VIP) in rat temporomandiblar joint (TMJ) was examined in intact rats and in rats subjected to removal of superior cervical ganglion by both avidinbiotin peroxidase procedure and indirect immunofluorescence technique using confocal laser scanning microscopy. The innervation pattern of NPY- and TH-positive fibers differed from that of VIP positive fibers, namely, former fibers distributed to both superficial and deep sublinig layr while latter mostly located deeper sublining layr. NPY- and TH-immunoreactive fibers were largely confined to vascular elements ; occasional fibers were observed in synovial lining layr close to joint cavity. Number of nerves with NPY- and TH-LI were more observed close to the upper joint compartment rather than to the lower compartment. NYP and TH-immunoreactivities were dramatically reduced in the TMJ of superior gaglionectomized animals, indicating the sympathetic origin of these nerves. These peptides might be involved in vascular regulatory and modulatory function in physiological and pathophysiological conditions.Second, to know the postnatal developmental (0-32 days) changes of the distribution of nerves and the synovial membrane, the distribution of nerves with the immunoreactivities of substance P (SP) -, calcitonin gene-related peptide (CGRP) -, and NPY was investigated. In the synovial membrane SP- or CGRP-immunoreactive fibers were observed at day 3, while NPY-immunoreactive nerves were observed at day10. Thus, sensory SP- or CGRP- fibers innervate earlier than the sympathetic NPY fibers.