Glucagon-like Peptide-1 Receptor Expression in the Pancreatic D Cells of Three Avian Species; White Leghorn Chickens, Northern Bobwhites, and Common Ostriches.

Glucagon-like peptide (GLP)-1 is released from the intestinal L cells in response to food ingestion and stimulates insulin secretion from the pancreatic B cells, by binding to its specific receptor (GLP-1R), which is expressed on the pancreatic B cells in the mammalian pancreas. Previously, we demonstrated that chicken GLP-1R was expressed on the pancreatic D cells by using a specific antibody against chicken GLP-1R. In the present study, we compared the localization of GLP-1R in the pancreases of three avian species; white leghorn chicken, northern bobwhite, and common ostrich, using the double immunofluorescence technique. We found that the types of pancreatic islets in the northern bobwhite pancreas were similar to those found in the chicken pancreas. The ostrich pancreas contained several types of pancreatic islets. GLP-1R-immunoreactive cells were found in all types of pancreatic islets in both northern bobwhite and ostrich and expressed somatostatin immunoreactivity. The present results indicate that the pancreatic D cells are the target cells of GLP-1, and GLP-1 might play a physiological role via somatostatin in the avian species.