title: Enterochromaffin-like cell carcinoids of gastric mucosa in rats after life-long inhibition of gastric secretion.
abstract: Small intramucosal tumours in the oxyntic area of the rat stomach were observed in an oncogenicity study with omeprazole. The tumours could be defined as carcinoids of enterochromaffin-like (ECL) cell origin. ECL cells occur exclusively in oxyntic mucosa and respond to the trophic hormone gastrin with a proliferation that becomes exaggerated in old rats. Inhibition of gastric acid secretion is known to induce hypergastrinaemia in rats. According to the common concept of endocrine cells, a sustained hormonal stimulation with gastrin may induce a continuous gradient between hyperplasia and neoplasia of the ECL cells. The tumours found are thus to be regarded as hormone-induced endocrine tumours of the ECL cells in the stomach. The ECL-cell tumours of the rats in the oncogenicity study appeared to belong to the low-malignancy type of carcinoids and did not make their appearance until the end-life period of the study. The sex and species differences observed may be explained by inherent differences in gastrin response, spontaneous ECL cell density or in responsiveness to gastrin-stimulated ECL cell proliferation between sexes and species.
mesh_terms: D000818:Animals; D002276:Carcinoid Tumor / Q000473:pathology*; D002838:Chromaffin System / Q000473:pathology*; D004759:Enterochromaffin Cells / Q000473:pathology*; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism / Q000473:pathology*; D005755:Gastrins / Q000097:blood; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D009853:Omeprazole; D051381:Rats; D011919:Rats, Inbred Strains; D012727:Sex Characteristics; D013045:Species Specificity; D013274:Stomach Neoplasms / Q000473:pathology*
chemical_list: D005755:Gastrins; D009853:Omeprazole