GABA

Stands for Gamma-aminobutyric acid, which is the major inhibitory neurotransmitter of the human central nervous system. Regulates neuronal excitability and muscle tone. GABA receptors can either be ion channels themselves- GABA_A and GABA_C act here, or metabotropic G-protein coupled receptors, which act indirectly at ion channels- GABA_B.