γ-aminobutyric acid

γ-ami·no·bu·tyr·ic ac·id (GABA) (ə-me″no-bu-tērґik) an ω-amino acid formed in the metabolism of L-glutamic acid; it is the principal inhibitory neurotransmitter in the brain but is also found in several extraneural tissues, including kidney and pancreatic beta cells. In the brain, it is released from presynaptic cells upon depolarization, and via receptor binding it modulates membrane chloride permeability and inhibits postsynaptic cell firing. Called also 4-aminobutyric acid.