Immunohistochemical localization of GABAA receptors in the mammalian crista ampullaris.

The distribution of GABAA receptor-like immunoreactivity in the hamster, rat, and mouse crista ampullaris was determined by use of a monoclonal antibody to the beta 2 and beta 3 subunits of the GABAA receptor. In the crista ampullaris, punctate staining was seen associated with the calyces surrounding vestibular type I hair cells. Afferent nerve fibers approaching the hair cell layer were often observed to be immunoreactive. Hair cells, supporting cells, and cells in the transitional and dark cell regions were not immunoreactive. The distribution of staining of calyces appeared to be relatively uniform in all regions (crest and slope) of the crista. In addition, cell bodies located in the vestibular ganglion were immunoreactive. The association of GABAA receptor-like immunoreactivity with the afferent nerve calyx and cell body of the vestibular ganglion cells suggests that GABA may act to modify afferent nerve transmission at the calyceal afferent nerve ending.