Immunocytochemical study of the GABA system in chicken vestibular endorgans and the vestibular ganglion

Abstract

The immunocytochemical distribution of γ-aminobutyric acid (GABA), GABA synthesizing enzyme; l-glutamate decarboxylase (GAD) and degradative enzyme; GABA transaminase (GABA-T) in the chicken vestibular endorgans and the vestibular ganglion was investigated. GABA and GAD-like immunoreactivity were confined to the sensory hair cell cytoplasm, suggesting that GAD synthesizes GABA in the hair cell. GABA-T-like immunoreactivity, indicative of GABA degradation, was found around hair cells, along nerve fibers running through the stroma and within the ganglion cell. These immunocytochemical findings indicate that the GABAergic system exists in the chicken vestibular endorgans and that GABA may function as an afferent neurotransmitter at the level of hair cells.