Tyrosine hydroxylase immunoreactivity identifies possible catecholaminergic fibers in the organ of Corti.

Antibodies to tyrosine hydroxylase, dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase were used in an immunocytochemical examination of catecholamines in the cochlea. In cryostat sections, tyrosine hydroxylase and dopamine beta-hydroxylase-like immunoreactivities fibers were seen in the modiolus that did not extend to the organ of Corti. These corresponded to blood vessel-associated and non-blood vessel-associated fibers that have been previously described with histofluorescence. In surface preparations, tyrosine hydroxylase-like immunoreactivity was seen in the organ of Corti, in the inner and tunnel spiral bundles, suggesting an efferent component may be catecholaminergic.