Secretin

also known as: SCT, Human secretin

The first hormone ever discovered — a 27-amino-acid gut peptide that stimulates pancreatic bicarbonate secretion and opened the entire field of endocrinology in 1902.

A 27-amino-acid peptide released by S-cells of the duodenum in response to gastric acid that stimulates pancreatic bicarbonate and bile secretion, inhibits gastrin, and is FDA-approved as a diagnostic agent for pancreatic function and gastrinoma.

Mechanism of action

Binds the secretin receptor (SCTR), a class B GPCR coupled to Gs/adenylyl cyclase/cAMP. In pancreatic duct cells, stimulates bicarbonate and water secretion. In the stomach, inhibits gastrin release. In the liver, stimulates bile flow.

Primary uses

Endogenous pancreatic bicarbonate secretion
Diagnostic: secretin stimulation test for gastrinoma
Diagnostic: pancreatic function testing
Historical significance: first hormone ever identified (1902)

Typical dosing

0.2-0.4 mcg/kg single diagnostic dose (IV)

Diagnostic use only: 0.2 mcg/kg IV for gastrinoma testing.

Regulatory status

Synthetic human secretin (SecreFlow/ChiRhoStim) is FDA-approved as a diagnostic agent for pancreatic exocrine function testing, gastrinoma localization, and facilitating MRCP imaging. First discovered by Bayliss and Starling in 1902 — the experiment that coined the word 'hormone.'

References

[pubmed] Bayliss WM, Starling EH. "The mechanism of pancreatic secretion." J Physiol. 1902;28(5):325-353.
[review] Afroze S, et al. "The physiological roles of secretin and its receptor." Ann Transl Med. 2013;1(3):29.

Related peptides

Cholecystokinin

The original satiety signal — a gut-brain peptide that tells you to stop eating, stimulates digestion, and modulates anxiety and pain in the CNS.

Glucagon

The endogenous counter-regulatory hormone to insulin — FDA-approved for severe hypoglycemia (injectable GlucaGen, nasal Baqsimi, autoinjector Gvoke). Also the pharmacological template for GLP-1/glucagon dual agonists like Pemvidutide and Retatrutide.

VIP

An endogenous 28-amino-acid peptide with vasodilatory, bronchodilatory, and immunomodulatory effects; explored in sarcoidosis, CIRS/mold illness, and acute respiratory distress.

GLP-2

GLP-1's sibling hormone — a potent intestinal growth factor that drives gut epithelial repair, and the native molecule behind teduglutide (Gattex).

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.