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

TLDR

The study aimed to develop specific antibodies and RIAs for GLP‑1 and GLP‑2 and to investigate their occurrence, nature, and secretion in pig pancreas and small intestine. The authors used these assays to analyze immunoreactive GLP‑1 and GLP‑2 in tissue extracts and perfused organs, assessing secretion during arginine, glucose, and gastrin‑releasing peptide stimulation. GLP‑1 and GLP‑2 immunoreactivity was detected in pancreatic islet glucagon cells and intestinal glicentin cells; intestinal GLP‑1 matched synthetic size, GLP‑2 differed, and pancreatic extracts contained a large peptide reactive to both; secretion of GLP‑1 and GLP‑2 mirrored glucagon and glicentin with matching molecular forms. Published in Endocrinology, 1986, vol.

Abstract

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). Immunoreactive GLP-1 and GLP-2 were secreted in parallel with pancreatic glucagon and intestinal glicentin. The molecular forms of secreted immunoreactive GLP-1 and 2 corresponded to those identified in the tissue extracts. (Endocrinology119: 1467–1475, 1986)