Somatostatin Characteristics
Option D is correct: Somatostatin inhibits gastric motility, along with endocrine, exocrine, pancreatic, and pituitary secretions, and modifies memory formation in the CNS. 1, 2
Analysis of Each Option
Option A: Production by Antral G Cells - INCORRECT
- Somatostatin is not produced by antral G cells 3
- G cells produce gastrin, while somatostatin actually inhibits gastrin release from these cells 3
- Somatostatin is produced by D cells in the gastric antrum and functions as part of the gastrin-acid feedback loop 2
Option B: Half-life of 30 Minutes - INCORRECT
- Native somatostatin has an extremely short half-life of 1-3 minutes, not 30 minutes 4, 5
- This very short half-life necessitates continuous intravenous infusion for clinical use 2, 4
- The synthetic analogue octreotide has a longer half-life of approximately 1.5-2 hours 1, 4
Option C: Increases Portal Blood Flow - INCORRECT
- Somatostatin decreases splanchnic blood flow, not increases it 1, 4
- Octreotide reduces splanchnic blood flow in healthy volunteers and hepatic venous pressure in cirrhotic patients 4
- This property is utilized therapeutically in variceal bleeding management 2
Option D: Inhibits Gastric Motility and Multiple Secretions - CORRECT
- Somatostatin has broad inhibitory effects on gastrointestinal motility 1, 2
- It inhibits gastric, biliary, and pancreatic secretions 1
- It suppresses endocrine secretions including growth hormone, insulin, glucagon, gastrin, and thyroid-stimulating hormone 1, 6, 4
- It inhibits exocrine pancreatic function (amylase, trypsin, lipase) 4
- It has effects on CNS function and memory formation 2, 7
Clinical Significance
The comprehensive inhibitory profile of somatostatin explains its therapeutic utility in multiple conditions 2, 5:
- Neuroendocrine tumors: Controls hormone hypersecretion syndromes 1
- High-output jejunostomy: Reduces fluid and electrolyte losses 1
- Variceal bleeding: Decreases splanchnic blood flow 2
- Acromegaly: Suppresses growth hormone secretion 1, 6
The short half-life limitation has been overcome with long-acting formulations (octreotide LAR, lanreotide) that can be administered every 4 weeks 1.