GABA-like immunoreactivity in the chick vestibular end organs.

gamma-Aminobutyric acid (GABA)-like immunoreactivity in the chick vestibular endorgans was examined using an antiserum against GABA coupled with glutaraldehyde to bovine serum albumin. GABA-like immunoreactivity was confined to the cytoplasm of the hair cells in both cristae and maculae. GABA-like immunoreactive cells were evenly distributed throughout the sensory epithelia, and no difference existed between type I and type II hair cells. The results provide evidence that GABA-like immunoreactivity is localized to sensory cells and raises the possibility that GABA may serve as an afferent neurotransmitter in the chick vestibular end organs.