GABA is the main inhibitory neurotransmitter found in the brain.1,2 GABA is synthesised predominantly from glutamate, by the enzyme glutamate decarboxylase.1 The ionotropic GABA receptors are inhibitory, because when activated they allow the flow of negatively charged chloride ions across the membrane – reducing the probability of action potential initiation in postsynaptic neurons.3
Chemicals that function as GABA agonists have been used to treat various conditions, and include anticonvulsants, anxiolytics, benzodiazepines, and hypnotics.4
GABA is distributed throughout most areas of the brain, rather than being localised to specific areas or pathways.2 There are three types of GABA receptor, which although varied can typically be separated as follows:3,7
- GABAA – ionotropic chloride channel
- GABAB – metabotropic G-protein-coupled receptor
- GABAC – ionotropic chloride channel.
Glycine, the other major inhibitory neurotransmitter, has a more localised distribution (about half of the inhibitory synapses in the spinal cord use glycine), and is a co-factor for activation of NMDA receptors.1,8
References:
1. Neurotransmitters. In: Kandel ER, Koester JD, Mack SH, Siegelbaum SA (eds). Principles of Neural Science. 6th edition. McGraw-Hill, 2021.
2. Ochoa-de la Paz LN, Gulias-Cañizo R, D´Abril Ruíz-Leyja E, et al., The role of GABA neurotransmitter in the human central nervous system, physiology, and pathophysiology. Revista Mexicana de Neurociencia 2021; 22 (2): 67–76.
3. Jewett BE, Sharma S. Physiology, GABA. StatPearls [internet]. 2023.
4. Chen RJ, Sharma S. GABA receptor. StatPearls [internet]. 2025.
5. Paul MS, Limaiem F. Histology, Purkinje Cells. StatPearls [Internet]. 2025.
6. The Cerebellum. In: Kandel ER, Koester JD, Mack SH, Siegelbaum SA (eds). Principles of Neural Science. 6th edition. McGraw-Hill, 2021.
7. Qian H. GABA-C receptors in the vertebrate retina. StatPearls [internet]. 2007.
8. Neurotransmitters. In: Augustine GJ, Groh J, Huettel S, et al. (eds). Neuroscience. 7th edition. Oxford University Press, 2023.