In the central nervous system, especially in the spine, glycine is an inhibitory neurotransmitter. Glycine and glutamate are both agonists in the central nervous system. Glycine amino acid has historically been considered to be the most important inhibitory neurotransmitter besides GABA. Glycine is widely distributed in the CNS and plays an important basic role in the transmission of nerve signals and in various physiological and pathological responses.