The Ferrier Lecture, 1983. Amino acids and peptides: fast and slow chemical signals in the nervous system?

The classical monoamine neurotransmitters, acetylcholine and the catecholamines, are used by only a small proportion of synapses in mammalian c.n.s. The amino acids GABA (gamma-aminobutyric acid) and L-glutamate may be the principal inhibitory and excitatory neurotransmitters used for fast point-to-point transmission in the c.n.s. The monoamines and the large number of neuropeptides (over 30) now known to exist in c.n.s. may be chemical signals used for a different type of chemically addressed form of information transmission between neurons in c.n.s. characterized by less precise spatial connections, a slower time course and a far richer diversity of chemical signals than used in classical synaptic neurotransmission. In this context the brain can be viewed as a neuroendocrine secretory organ of great complexity.