Secretin

Abstract

Secretin is one of the "classical" gastrointestinal hormones and in fact was the first peptide hormone identified. The mature hormone is a 27 amino acid peptide produced and secreted by a specific type of enteroendocrine cell, the S cell which is of the open type with its apical surface exposed to luminal content. Secretin is packaged into granules and released across the basolateral membrane into the blood in response to acid in the duodenum when the pH falls below 4.5; it is also released in response to fatty acids but without a response to glucose or amino acids. Basal and stimulated concentrations are low normally in the 1-10 pM range. The principal action of secretin is to stimulate bicarbonate secretion by pancreatic and biliary ducts and duodenal Brunner's glands into the lumen such that acid in the duodenum will be neutralized. Secretin also acts to potentiate CCK action on acinar cells, to inhibit gastric acid secretion and to inhibit gastric emptying. Secretin also has actions in the brain. At the cellular level the action of secretin is primarily mediated by cAMP which is increased in response to activation of secretin receptors.

Two novel bombesin-like neuropeptides from the skin secretion of Pelophylax kl. esculentus: Ex vivo pharmacological characterization on rat smooth muscle types

“…Amphibian skin-derived neuropeptides, including bombesin, bradykinin, litorin, caerulein, tachykinin, tryptophyllin, dermorphin, and deltorphin, have been considered part of their host-defense system and display a wide range of biological effects on various physiological processes ( Pukala et al, 2006a ; Bilusich et al, 2009 ). Bombesin-like peptides (BLPs), derived from amphibians, which function via activating G-protein-coupled receptors, have been shown to modulate multiple pharmacological effects on smooth muscles in various organs, including blood vessels, the stomach, intestines, the bladder, airways, and the uterus ( Bardin, 1993 ; Williams, 2015 ).…”