Acetylcholine receptor localization in human adult cochlear and vestibular hair cells

The FITC technique using alpha-bungarotoxin visualized the staining pattern of acetylcholine (ACh) receptors in adult human cochlear and vestibular hair cells (HCs) in normal labyrinths and in cochleae with sensorineural hearing loss. Flourescence staining occurred in the cuticular plates of all HCs, indicating that the micromechanics of their suprastructures can act under cholinergic control. Quantitative differences of the fluorescence of ACh receptors occurred between the three rows of outer HCs at the same level in the cochlea and decreasing along a base-to-apex directed gradient. There is strong evidence that the subsurface cisterns are integrated in the efferent nerve system. In the degenerating organ of Corti an uncoupling of the efferent system takes places adjacent to disintegrating HCs, though the staining in the cuticular plates remains until a very late stage in HC disintegration. In vestibular HCs type I, fluorescence is emitted in the supranuclear area of the cytoplasm below the cuticular plate probably indicating an efferent guidance on the afferent nerve transmission directly via the HC itself.