Glucagon-like peptide 2 is released from intestinal L cells alongside GLP-1 from the same proglucagon precursor, but its actions are quite different: rather than regulating insulin secretion, it is trophic to the intestinal epithelium, increasing mucosal mass and absorptive capacity. That property carried it into the clinic. The discovery of GLP-2 led directly to the development of teduglutide for short bowel syndrome, a condition in which insufficient intestinal surface leaves patients dependent on parenteral nutrition, and studies of teduglutide have examined its acute effects on intestinal adaptation in those patients. The reason an analogue was needed rather than the native peptide is visible in the supplied sequence: the second residue is alanine, the position at which dipeptidyl peptidase-4 cleaves, giving the native peptide a short circulating half-life. Teduglutide substitutes glycine there to resist that cleavage. For experimental work this means the native peptide behaves quite differently from the analogue in any system containing DPP-4 activity, which includes plasma and many tissue preparations. Where sustained exposure is required, either include a DPP-4 inhibitor or expect rapid degradation; where the question is the native peptide's own pharmacology, this product is the correct reagent. | 