NCIt definition : A naturally occurring neurotransmitter with central nervous system (CNS) inhibitory
activity. Gamma-aminobutyric acid (GABA), converted from the principal excitatory
neurotransmitter glutamate in the brain, plays a role in regulating neuronal excitability
by binding to its receptors, GABA-A and GABA-B, and thereby causing ion channel opening,
hyperpolarization and eventually inhibition of neurotransmission.;