AMINO ACID TRANSMITTERS

There are 4 amino acids  which have been documented as being the transmitter for
specific brain and spinal cord circuits.  Two amino acid transmitters, aspartate 
and  glutamate, are excitatory  in their actions; both are dicarboxylic amino
acids.  The other two amino acid transmitters, glycine  and gamma-aminobutyrate
(or more commonly GABA) are inhibitory, and are the mono-carboxylic acid forms of
aspartate and glutamate, respectively. These amino acids are found in the brain
in amounts concentrations of µM/mg protein.