Which statement correctly describes paracrine interactions among the endocrine cells of a pancreatic islet?

• A Insulin released from beta cells stimulates neighboring alpha cells to secrete glucagon
• B Somatostatin released from delta cells inhibits secretion of both insulin and glucagon ✓
• C Glucagon released from alpha cells inhibits insulin secretion from beta cells
• D Pancreatic polypeptide released from F cells is the main inhibitor of insulin release

Explanation

Delta cells scattered within the islet release somatostatin, which exerts tonic paracrine inhibition on both beta and alpha cells, damping insulin and glucagon output after nutrient absorption. Insulin actually suppresses glucagon secretion, and glucagon locally stimulates beta cells, so both directions in the other options are reversed. Pancreatic polypeptide mainly modulates gastrointestinal and exocrine secretion and is not the principal brake on insulin.

Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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