Gastrointestinal endocrinology.

During the last quarter of this century gastrointestinal endocrinology has grown explosively. In 1970, three hormones (secretin, gastrin, and cholecystokinin) were identified and by authorities in the field considered sufficient to explain the entire hormonal regulation of digestion. That was some underestimation. Today the gut is known to express more than 20 different hormonal/regulatory peptide systems. Their widespread cellular occurrence, gene expression cascades, secretory mechanisms, receptors and receptor binding, as well as normal and pathophysiological effects are now also fairly well known owing to the marked progress in basic sciences and biochemical technologies (immuno and peptides chemistry, molecular and cell biology). Thus, the gut is now recognized as the largest endocrine organ of the body; and a substantial part of the gastroenterologic research over the latest decades has been devoted to gut hormones. The following review describes the recent development, with emphasis on gastrointestinal peptide systems that have been studied and even discovered in Denmark. Hence, as reflected by the number of doctoral theses and PhD studies (> 50 since 1974), gastrointestinal endocrinology has been a major research area in this country in the past 25 years.