title: Localization of chat-like immunoreactivity in the vestibular endorgans of the rat.
abstract: In vertebrates acetylcholine (ACh) has been generally considered as a neurotransmitter of the vestibular efferent system. The precise localization and innervation of the cholinergic nerve endings in the vestibular sensory periphery is still unknown. We examined choline acetyltransferase (ChAT)-like immunoreactivity in all five endorgans of the rat vestibule with light and electron microscopy using a modified pre-embedding immunostaining technique. The results were: (1) ChAT-like immunoreactivity was widespread in all five endorgans of the vestibule and confined to the vesiculated efferent nerve endings. (2) Two types of ChAT-like immunostained nerve endings can be identified according to their size and innervation pattern: a large nerve ending and a small--middle size one. (3) Vestibular endorgans differ in their ChAT-like immunoreactivity: staining is dense in the macula of the utricule and the three ampullary cristae, but less so in the macula of the saccule. (4) We found also a regional difference of the ChAT-like immunostaining in ampullary crista. ChAT-like immunostained nerve endings were predominant in the periphery close to the semilunar plane, and less in density in the central area. These findings demonstrate that ACh is a major neurotransmitter in the vestibular efferent system.
authors.affiliation: Department of Otolaryngology, University of Innsbruck, Austria.
authors.forename: W J
authors.initials: WJ
authors.lastname: Kong
authors.forename: G
authors.initials: G
authors.lastname: Egg
authors.forename: B
authors.initials: B
authors.lastname: Hussl
authors.forename: H
authors.initials: H
authors.lastname: Spoendlin
authors.forename: A
authors.initials: A
authors.lastname: Schrott-Fischer
mesh_terms: D000818:Animals; D002795:Choline O-Acetyltransferase / Q000378:metabolism*; D005260:Female; D006198:Hair Cells, Auditory / Q000201:enzymology / Q000648:ultrastructure; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000201:enzymology* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014722:Vestibule, Labyrinth / Q000294:innervation* / Q000648:ultrastructure
chemical_list: D002795:Choline O-Acetyltransferase