Peptides with a dual function: Central neuroregulators and gut hormones

The present article deals with peptides which are present in the CNS and in various peripheral tissues in neuronal as well as in endocrine cells. The regional distribution within the central nervous system is analysed, the cellular structures in which they are found are summarized and their actions are mentioned. As this branch of physiology has taken a lofty flight, we do not seek completeness. Selected aspects of the discussed peptides are considered and the number of references will be kept limited, giving preference to those articles which refer to earlier original work. It is the purpose to illustrate the inseparability of neuroregulatory and endocrine actions of certain endogenous substances. Concepts, which explain this dual function are discussed and some possible consequences are evaluated. The structure of the discussed peptides and localisation of these peptides in the gastroentero-pancreatic system and the central nervous system are given at the end of this review