The immunocytochemical distribution of γ-aminobutyric acid (GABA), GABA synthesizing enzyme; glutamic acid decarboxylase (GAD) and degradative enzyme; GABA transaminase (GABA-T) in the guinea pig organ of Corti was investigated.
Although GABA-like immunoreactivity was found predominantly in the third and fourth turn, GAD and GABA-T-like immunoreactivity was present throughout all turns of the cochlea. These findings indicate GABA system may play an important role not only in the apical turn but also in the lower turn.