Because amino acids are used for protein synthesis by all cells of the brain, it is difficult to prove that a particular amino acid is a transmitter substance. Eight amino acids have been discovered to serve as transmitters, but we will only discuss three of them. A. Glutamic acid Principle excitatory transmitter substance in the brain. Appears to play a role in learning and memory. Inhibitory transmitter that has widespread distribution throughout the brain and spinal cord.
Inhibitory neurons are necessary for stabilizing the electrical activity.
One type of GABA receptor opens the chloride ion channels and another type opens potassium channels. C. Glycine Inhibitory transmitter in the spinal cord and lower portions of the brain. Several different peptides are released by neurons of the central nervous system. Although most peptides appear to serve as neuromodulators, some act as neurotransmitters. In comparison with the other transmitters described, synthesis of peptides requires gene activation, DNA transcription, and RNA translation, with the final peptide being transported from soma to release sites.