title: Enterochromaffin (EC-) cells of the mammalian gastro-entero-pancreatic (GEP) endocrine system: cellular source of pro-dynorphin-derived peptides.
abstract: It has long been disputed whether mammalian enterochromaffin (EC-) cells contain a peptide in addition to serotonin. Previous immunohistochemical studies have provided evidence for the presence of enkephalins in EC-cells. These findings, however, are equivocal. Therefore, the problem of opioid peptides in EC-cells has been re-examined in the gastro-intestinal mucosa of dog, guinea-pig and man. A battery of antisera against derivatives of pro-opiomelanocortin, pro-enkephalin and pro-dynorphin have been applied to semithin serial sections of the tissues, in combination with fluorescence histochemistry and serotonin immunocytochemistry. Our findings indicate that EC-cells of the investigated species contain pro-dynorphin-related peptides, i.e. dynorphin A and alpha-neo-endorphin, but no derivatives from pro-opiomelanocortin or pro-enkephalin. Since remarkable interspecies variations occur with respect to the number and staining characteristics of opioid immunoreactive EC-cells, it is concluded that pro-dynorphin shows specific routes of post-translational processing depending upon the species and the gastro-intestinal segment investigated. Future studies should focus on the mutual relationships between serotonin and dynorphins and on the physiological significance of these peptides in the gastrointestinal tract.
mesh_terms: D000313:Adrenal Medulla / Q000166:cytology; D000818:Animals; D002417:Cattle; D002838:Chromaffin System / Q000648:ultrastructure*; D004064:Digestive System / Q000166:cytology*; D004285:Dogs; D004399:Dynorphins / Q000032:analysis / Q000276:immunology; D004723:Endorphins / Q000032:analysis / Q000276:immunology; D004745:Enkephalins / Q000032:analysis / Q000276:immunology*; D004759:Enterochromaffin Cells / Q000648:ultrastructure*; D006168:Guinea Pigs; D006801:Humans; D007150:Immunohistochemistry; D010179:Pancreas / Q000166:cytology*; D010902:Pituitary Gland / Q000166:cytology; D011333:Pro-Opiomelanocortin / Q000032:analysis / Q000276:immunology; D011498:Protein Precursors / Q000032:analysis / Q000276:immunology*
chemical_list: D004723:Endorphins; D004745:Enkephalins; D011498:Protein Precursors; C029992:proenkephalin; D011333:Pro-Opiomelanocortin; C025681:alpha-neoendorphin; D004399:Dynorphins; C033660:preproenkephalin