With the discovery of an ever increasing number of biogenetic polypeptides in the autonomic nervous system, it is evident that nervous transmission is controlled and modified not only by a series of classical transmitters but also by a variety of co-transmitters and modulators. Purifi- cation, characterization and synthesis of neuropeptides and peptide families allows the application of specific anti- bodies for radioimmunological, immunohistochemical and immunocytochemical localization. Transmitter interactions and phenotypic neuronal plasticity can be analyzed by pharmacological or surgical...