Gut hormones in disease

The anatomical basis of gastrointestinal neuroendocrinology is formed by mucosal endocrine cells and the mainly intrinsic enteric nerves. The endocrine cells contain electron-dense secretory granules which are characteristic of each peptide being produced by the separate cell types. The peptides produced by these neuroendocrine elements act in a tripartite manner; via the blood stream, locally or as neurotransmitters. Investigation of the actions of these peptides necessitates development of new physiological approaches. Furthermore, the interplay, whether agonistic or antagonistic, between the elements and hormones must be taken into account. Technological developments have provided new means for the investigation of the diffuse neuroendocrine system of the gut. This system can now be visualised in its entirety using the simple marker, neuron-specific enolase (NSE). Advances in the chemical characterisation of peptides have enabled the subsequent raising of antibodies to various specific fragments of hormones and prohormones. In addition, new immunocytochemical methods, in particular the use of gold particulate markers, enables us now to visualise the intracellular events of peptide biosynthesis. It is evident that more regulatory peptides are being discovered and application of new immunological probes, eg monoclonal antibodies, will reveal the total extent of the diffuse neuroendocrine system and its possible abnormalities in disease states, thereby opening new vistas in clinical endocrinology.