Glucagon-like peptide-1 (GLP-1) is a 30- or 31-amino-acid-long peptide hormone deriving from tissue-specific posttranslational processing of the proglucagon peptide.
Gastric inhibitory polypeptide (GIP) andglucagon‐like peptide‐1 (GLP‐1) are the two primary incretin hormones secreted from the intestine on ingestion of glucose or nutrients to stimulate insulin secretion from pancreatic βcells.
GLP-1-inducedK. AT P. channel closure and adenylyl cyclase ac IntactGLP-1, GIP, and dipeptidyl peptidase (DPP)-IV were measured by ELISA. T2DM exhibited an impaired early phase of insulin secretion and a reduction inglucagonsuppression.
Additionally, this signaling cascade promotesbeta-cellsurvival and improves their function, which is critical in preventingbeta-cellexhaustion often seen in T2DM.[126,127]GLP-1not only stimulates insulin secretion but alsosuppressesglucagonrelease from pancreatic alphacells.
Notably, GK islets still hypersecretedglucagonafterGLP-1treatment (Fig. 2b). The densitometric analysis showed thatGLP-1induceda pronouncedsuppressionof both ncNOS and iNOS expression in GK islets.
Glucagon-like peptide-1inducescellproliferation and pancreatic-duodenum homeobox-1expression and increases endocrinecellmass in the pancreas of old, glucose-intolerant rats. Endocrinology 2000; 141: 4600-5.
The incretin hormones includeglucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), both of which may also promote proliferation/neogenesis ofbetacellsand prevent their decay (apoptosis).
GLP-1(28-36) improvesbeta-cellmass and glucose disposal in streptozotocin-induceddiabetic mice and activates cAMP/PKA/beta-catenin signalinginbeta-cellsin vitro. Am J Physiol Endocrinol Metab. (2013) 304:E1263–72.
