Glucagon-Like Peptides GLP-1 and GLP-2, Predicted Products of the Glucagon Gene, Are Secreted Separately from Pig Small Intestine but Not Pancreas

We developed specific antibodies and RIAs for glucagon-like peptides 1 and 2 (GLP-1 and GLP-2), two predicted products of the glucagon gene, and studied the occurrence, nature, and secretion of immunoreactive GLP-1 and GLP-2 in pig pancreas and small intestine. Immunoreactive GLP-1 and GLP-2 were identified in glucagon-producing cells of the pancreatic islets, and in glicentin-producing cells of the small intestine. Immunoreactive GLP-1 and 2 in intestinal extracts corresponded in molecular size to peptides synthesized according to the predicted structure. By reverse phase HPLC, intestinal and synthetic GLP-1 behaved similarly, whereas synthetic and intestinal GLP-2 differed. Pancreatic extracts contained a large peptide with both GLP-1 and GLP-2 immunoreactivity. Secretion was studied using isolated perfused pig pancreas during arginine stimulation, and isolated perfused pig ileum during either luminal glucose stimulation or vascular administration of the neuropeptide, gastrin-releasing peptide (GRP). Im...