Abstract
Glucagon-like peptide-1 (GLP-1) is a peptide hormone of the incretin group. Its main effects on physiological processes include increased glucose-dependent insulin secretion, proliferative and antiapoptotic effects in β-cells of the islets of Langerhans (described in experiment), inhibition of gastrointestinal tract motility and decreased appetite.
Production of GLP-1 is located in specialized intestinal enteroendocrine L-cells that are abundant in terminal ileum and oral sections of the colon. The main stimuli for GLP-1 production and secretion are nutrients in chyme, in particular saccharides and lipids.
Peptones, some amino acids (esp. glutamine and branched chain amino acids) or bile acids have their role in the regulation also. Membrane and cytoplasm of the L-cells is equipped with a number of specific proteins that can sense a presence of these substances in the lumen of the GIT and start process of release of GLP-1 to the blood circulation.
These findings led to the targeting of the incretin system for the treatment of diabetes mellitus - so called incretin-based therapies. Two approaches are available nowadays: GLP-1 analogues resistant to degradation by the enzyme dipeptidyl peptidase-4 (DPP IV) and DPP IV inhibitors.