Localization of glucagon-like peptide-2 receptor mRNA expression at different sites in the small intestine of rats

Preproglucagon is known to be processed into glucagon-like peptide (GLP)-1, GLP-2, and glicentin in the L cells of the intestinal tract. GLP-2 has been shown to possess intestinotrophic activity in rodents. However, the ligand-binding mechanisms of GLP-2 receptor (GLP-2R) have not been extensively investigated. The present study sought to determine the localization of GLP-2R in the small intestine by analyzing GLP-2R mRNA expression using the reverse transcriptase-polymerase chain reaction (RT-PCR) method. GLP-2R mRNA expression was detected at all sites in the small intestine; its expression levels were particularly high in the jejunum. Moreover, GLP-2R mRNA expression was detected in both non-mucosal intestinal tissues and intestinal mucosa. These findings suggest that in addition to the intestinal mucosa, the functional sites of GLP-2 may be present in the non-mucosal tissues. These results imply that GLP-2 peptide acts as an intestinotrophic factor that may affect the intestines from outside the mucosa. The intestinotrophic effect of GLP-2 from outside the mucosa may be a function of the enteric neurons transmitting several growth signals to mucosal cells.