Somatostatin secreted by pancreatic delta cells reaches neighboring islet cells through the islet microcirculation. Its principal endocrine action within the islet is which of the following?
- A Inhibition of both insulin and glucagon secretion ✓
- B Stimulation of insulin secretion and inhibition of glucagon secretion
- C Stimulation of both insulin and glucagon secretion
- D Selective inhibition of insulin with no effect on glucagon
Correct answer: A. Inhibition of both insulin and glucagon secretion
Explanation
Pancreatic somatostatin acts through Gi-coupled receptors to suppress secretion of both insulin from beta cells and glucagon from alpha cells, damping overall islet output after nutrient ingestion. This differs from hypothalamic somatostatin, whose main target there is growth hormone. Selective effects on only one islet cell type do not occur, which eliminates options B and D.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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