Characterization of obestatin- and ghrelin-producing cells in the gastrointestinal tract and pancreas of rats: an immunohistochemical and electron-microscopic study

Cell Tissue Res. 2008 Mar;331(3):575-87. doi: 10.1007/s00441-007-0514-3. Epub 2007 Dec 11.

Abstract

Both ghrelin and obestatin are derived from preproghrelin by post-translational processing. We have morphologically characterized the cells that produce obestatin and ghrelin in new-born and adult Sprague-Dawley rats that were freely fed, fasted, or subjected to gastric bypass surgery or reserpine treatment. Tissue samples collected from the gastrointestinal tract and pancreas were examined by double-immunofluorescence staining, immunoelectron microscopy, and conventional electron microscopy. Obestatin was present in the stomach, duodenum, jejunum, colon, and pancreas. In the stomach, differences were noted in the development of obestatin- and preproghrelin-immunreactive (IR) cells on the one hand and ghrelin-IR cells on the other, particularly 2 weeks after birth. Preproghrelin- and obestatin-IR cells were more numerous than ghrelin-IR cells in the stomach, suggesting the lack of ghrelin in some A-like cells. Most obestatin-producing cells in the stomach were distributed in the basal part of the oxyntic mucosa; these cells co-localized with chromogranin A (pancreastatin) and vesicle monoamine transporters type 1 and 2, but not with serotonin or histidine decarboxylase. Immunoelectron microscopy revealed the obestatin- and ghrelin-producing cells to be A-like cells, characterized by numerous highly electron-dense granules containing ghrelin and obestatin. Some granules exhibited an even electron density with thin electron-lucent halos, suggestive of monoamines. Feeding status, gastric bypass surgery, and reserpine treatment had no obvious effect on the A-like cells. In the pancreas, obestatin was present in the peripheral part of the islets, with a distribution distinct from that of glucagon-producing A cells, insulin-producing beta cells, and cells producing pancreatic polypeptide Y. Thus, obestatin and ghrelin co-localize with an anticipated monoamine in A-like cells in the stomach, and obestatin is found in pancreatic islets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Chromogranin A
  • Enteroendocrine Cells / cytology
  • Enteroendocrine Cells / metabolism
  • Enteroendocrine Cells / ultrastructure
  • Fasting / metabolism
  • Gastric Bypass
  • Gastric Mucosa / cytology
  • Gastric Mucosa / metabolism
  • Gastrointestinal Tract / cytology*
  • Gastrointestinal Tract / metabolism
  • Ghrelin / metabolism*
  • Histidine Decarboxylase / metabolism
  • Immunohistochemistry
  • Intestinal Mucosa / metabolism
  • Intestines / cytology
  • Islets of Langerhans / cytology
  • Islets of Langerhans / metabolism
  • Male
  • Microscopy, Immunoelectron
  • Models, Biological
  • Pancreas / cytology*
  • Pancreas / metabolism
  • Pancreatic Hormones / metabolism
  • Peptide Hormones / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Serotonin / metabolism
  • Stomach / cytology
  • Vesicular Monoamine Transport Proteins / metabolism

Substances

  • Chromogranin A
  • Ghrelin
  • Pancreatic Hormones
  • Peptide Hormones
  • Slc18a1 protein, rat
  • Slc18a2 protein, rat
  • Vesicular Monoamine Transport Proteins
  • obestatin, rat
  • pancreastatin
  • Serotonin
  • Histidine Decarboxylase