The incretin effect refers to the greater insulin secretory response to oral glucose versus IV glucose at matching plasma glucose levels. Which receptor does GLP-1 activate to stimulate insulin secretion in a glucose-dependent manner?
- A GLP-1 receptor (GLP-1R) — a Gs-coupled GPCR activating adenylyl cyclase, raising cAMP ✓
- B GLUT-2 transporter acting as an intracellular signal transducer
- C Insulin receptor beta subunit tyrosine kinase
- D Sulfonylurea receptor (SUR-1) on ATP-sensitive K+ channels
Correct answer: A. GLP-1 receptor (GLP-1R) — a Gs-coupled GPCR activating adenylyl cyclase, raising cAMP
Explanation
GLP-1 binds the GLP-1 receptor, a Gs-coupled GPCR on pancreatic beta cells. This activates adenylyl cyclase, raising intracellular cAMP, which potentiates glucose-stimulated insulin secretion. The key feature is glucose-dependence — GLP-1 receptor activation only stimulates insulin when blood glucose is elevated, greatly reducing hypoglycemia risk compared to sulfonylureas. GLP-1 receptor agonists (exenatide, liraglutide, semaglutide) mimic this effect.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.