CHAPTER 153 – Secretin

Secretin is the first peptide hormone ever discovered. Secretin is a 27-amino-acid peptide of secretin-glucagon-vasoactive intestinal polypeptide superfamily and is localized mainly in the upper small intestinal mucosa. The gene structures of secretin and its receptor have been determined. Compared with several bio-active prosecretins, secretin is the most active form. The physiological functions of secretin include the stimulation of pancreatic exocrine secretion of water and electrolytes, inhibition of gastric acid secretion, and motility. The physiological release and actions of secretin are subjected to hormone-hormonal and neural-hormonal regulations, among which the vagal afferent pathway plays a significant role. Secretin is used clinically to assess pancreatic function and test for pancreatic malignancy. Pathological states of both hyposecretinemia and hypersecretinemia have been well documented.