[Immunohistochemical distribution and fine localization of the gamma-aminobutyric acid in the organ of Corti of normal guinea pigs]

Abstract

This paper presents the distribution and fine localization of the gamma-aminobutyric acid (GABA) in the Corti's organ of normal guinea pigs by using immunohistochemical technique (ABC-GDN method) and immunoelectron microscopy. GABA-IR was found in axons of efferent neurons in all turns of the cochlear spiral, but no positive endings may be found in the apical. The positive immunoreactive products were seen in the efferent components, including inner spiral bundle, tunnel spiral bundle, tunnel-crossing fibers, and large nerve endings on outer hair cell bases. Some of the GABA-IR negative outer hair cells could be seen between the positive endings. One GABA-IR positive nerve fiber could form synapse with six or seven outer hair cell bases. The GABA-IR positive efferent endings, negative efferent endings and negative afferent endings could be seen on the out hair cell bases with transmission electronic microscope. The GABA-IR positive efferent endings and negative afferent endings could form the neuraxon-neurodendron synapse on the inner hair cells bases. These morphological distribution suggests that the GABA may be one of the cochlear efferent neurotransmitter or modulator.