[Regulatory neuropeptides in the nerves and endocrine cells of the gastrointestinal tract].

Already at the beginning of this century a dualism of neural and endocrine regulation of the gastrointestinal tract was apparent. This dualism first characterized by I. P. Pavlov on the one side and W. M. Bayliss and E. H. Starling on the other has persisted in the present days. It is only recently that we begin to realize that neural and endocrine regulations represent no antipodes but a continuum. Neural, endocrine and paracrine transmission of chemical messengers form an integrated signal. This view is supperted by many peptides present both in nerves and endocrine cells and by neural regulation of endocrine hormone release. These interelationships are illustrated by experiments concerning the enkephalins, neurotensin and CCK. Concurrent with the evolution from bacteria to mammals the chemical messengers in the higher animals act in a complex organisation including neural, endocrine and paracrine mechanisms.