Transmitter-peptide coexistence in the central nervous system.

In this minireview about transmitter coexistence situations in central nervous system and peripheral sympathetically innervated tissues, the classical transmitters, dopamine, noradrenaline, adrenaline and serotonin, together with peptides such as substance P, cholecystokinin and avian pancreatic polypeptide, have been considered. The specificity of an immunohistochemical reaction for the identification of peptides and functional aspects of central transmitter peptide coexistence are discussed. In conclusion, in several experimental models it has been demonstrated that peptides, which are known to coexist with monoamines, exert specific effects in those regions where coexistence situations have been reported. In general, the effect of the co-stored peptides seems to be enhancement of the response caused by monoamines, indicating that two coexisting neuroactive substances cooperate in causing a certain physiological response.