Gamma-aminobutyric acid (GABA) is an amino acid that functions as the primary inhibitory neurotransmitter in the central nervous system (CNS). GABA is synthesized from the excitatory neurotransmitter glutamate and reduces neuronal excitability by causing neuronal hyperpolarization and decreasing neurotransmitter release. The activity of GABA is regulated by binding through 3 receptors—GABA-A, GABA-B, and GABA-C.

GABAergic neurons are located in the hippocampus, thalamus, basal ganglia, hypothalamus, and brainstem. Maintaining a balance between inhibitory neuronal transmission mediated by GABA and excitatory neuronal transmission mediated by glutamate is essential for maintaining cell membrane stability and proper neurological function. Disruption of the balance between glutamate and GABA has a functional role in various pathologies, including traumatic brain injury, Alzheimer disease, epilepsy, schizophrenia, and autism. The role of GABA receptors in analgesia is also being investigated.