RECIPROCAL CELLULAR-DISTRIBUTION OF GLUCAGON-LIKE PEPTIDE-1 (GLP-1) IMMUNOREACTIVITY AND GLP-1 RECEPTOR MESSENGER-RNA IN PANCREATIC-ISLETS OF RAT

The respective cellular distribution of glucagon like peptide-1 (GLP-1 ) immunoreactivity and mRNA expression of the GLP-1 receptor was compa red in rat pancreas by means of immunohistochemistry and in situ hybri dization. GLP-1 immunoreactivity was present in the marginal zone of r at pancreatic islets. In contrast, GLP-1 receptor mRNA signals were co nfined to the central part of pancreatic islets. Neither GLP-1 immunor eactivity nor GLP-1 receptor mRNA signals were detected in the exocrin e pancreatic acinar cells or duct cells. The differential distribution of GLP-1 immunoreactivity and GLP-1 receptor mRNA signals indicates t hat the GLP-1 amino acid sequences is present in the alpha-cell zone o f pancreatic islets, whereas the GLP-1 receptor is expressed mainly by beta cells. Thus, our data by in situ hybridization demonstrates the significant expression of GLP-1 receptors on beta cells but makes a si gnificant expression on a cells rather unlikely.