Gamma-Aminobutyric Acid (gABA)

γ-Aminobutyric acid (GABA) is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays an important role in regulating neuronal excitability throughout the nervous system. In humans, GABA is also directly responsible for the regulation of muscle tone.In insect species GABA acts only on excitatory nerve receptors.
Although chemically it is an amino acid, GABA is rarely referred to as such in the scientific or medical communities, because the term "amino acid," used without a qualifier, refers to the alpha amino acids, which GABA is not, nor is it incorporated into proteins. In spastic diplegia in humans, GABA absorption by some nerves becomes impaired, which leads to hypertonia of the muscles signaled by those nerves.Gamma-aminobutyric acid was first synthesized in 1883, and was first known only as a plant and microbe metabolic product.