DISTRIBUTION AND ORIGIN OF NERVE-FIBERS IN THE RAT TEMPOROMANDIBULAR-JOINT CAPSULE

The distribution and origin of nerve fibers containing neuropeptides a nd NOS projecting to the temporomandibular joint capsule (TMJ) of the rat were studied by retrograde tracing in combination with immunocytoc hemistry. Numerous nerve fibers were seen in the TMJ as revealed by th e neuronal marker protein gene product 9.5. Nerve fibers containing ne uropeptide Y (NPY), vasoactive intestinal peptide (VIP), pituitary ade nylate cyclase activating peptide (PACAP), substance P (SP), calcitoni n gene-related peptide (CGRP), and nitric oxide synthase (NOS) were se en in the synovial membrane, the joint capsule and entering the articu lar disc. Injection of the retrograde tracer True Blue (TB) into the T MJ resulted in the appearance of numerous labeled nerve cell bodies in the trigeminal and superior cervical ganglia, and moderate numbers in the nodose, the otic, the sphenopalatine, the stellate and the dorsal root ganglia at levels C2-C5. Most of the TB-labeled cell bodies in t he superior cervical and stellate ganglia contained NPY. In the trigem inal ganglion, numerous TB labeled cell bodies contained CGRP and a mi nor population stored SP a few cell bodies were seen to store NOS or P ACAP. In the sphenopalatine and otic ganglia, TB labeled cell bodies c ontained NOS or VIP. In the nodose ganglion, labeled cell bodies conta ined CORP, other labeled cell bodies harbored NOS. In the cervical dor sal root ganglia, the majority of the labeled cell bodies stored CGRP and smaller populations stored SP and PACAP. Thus, the innervation of the TMJ is complex and many different ganglia are involved.