| Hormones
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Tissues of Origin
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Dietary Functions
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Secretory Stimuli
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| Cholecystokinin
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Enteroendocrine I cells and enteric nerves
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- Inhibits proximal gastric motility while increasing antral and pyloric contractions
- Regulates meal-stimulated pancreatic enzyme secretion and gallbladder contraction
- Trophic effects on pancreatic acini in rats Postprandial satiety
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- Oral nutrient ingestion, especially lipids and proteins
- Several intestine-derived hormones, including GRP
- Activation of β-adrenergic receptors
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| Gastrin
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Enteroendocrine G cells of the stomach and duodenal bulb
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- Amidated gastrins are trophic to the oxyntic mucosa of the stomach
- Progastrin and glycine-extended gastrin induce colonic epithelial proliferation
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- Luminal contents, especially partially digested aromatic amino acids, small peptides, calcium, coffee, and ethanol
- Humoral and neural influences, including the vagus nerve, β-adrenergic and GABA neurons, and GRP
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| Gastric Inhibitory Polypeptide
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Neuroendocrine K cells in the duodenum and proximal jejunum
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- Inhibits gastric acid secretion and GI motility
- Increases insulin release and regulates glucose and lipid metabolism
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- Oral nutrient ingestion, especially long-chain fatty acids
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| Motilin
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Enteroendocrine M cells located in the duodenum and proximal jejunum
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- Induces phase III contractions in the stomach
- Stimulates gastric and pancreatic enzyme secretion
- Induces contraction of the gallbladder, sphincter of Oddi, and LES
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- Duodenal alkalinization, sham feeding, gastric distention; opioid agonists promote secretion
- Unlike most GI hormones, motilin is suppressed in the presence of duodenal nutrients
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| Secretin
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Enteroendocrine S cells located in the duodenum and proximal jejunum
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- Principal hormonal stimulant of pancreatic and biliary bicarbonate and water excretion
- Regulates pancreatic enzyme secretion
- Stimulates gastric secretion of pepsinogen
- Inhibits LES tone, postprandial gastric emptying, gastrin release, and gastric acid secretion
|
- Gastric acid, bile salts, and luminal nutrients, especially fatty acids, peptides, and ethanol
- Somatostatin inhibits secretion
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| Somatostatin
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Enteroendocrine D cells and pancreatic delta cells
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- Inhibits secretion of islet hormones, including insulin, glucagon, and PP
- Inhibits secretion of gut peptides, including gastrin, secretin,VIP, CCK, GLP1 and GLP2
- Inhibits pancreatic exocrine secretion Acts in a paracrine manner on G cells, enterochromaffin-like cells, and parietal cells to inhibit gastric acid secretion
- Reduces splanchnic blood flow, intestinal motility, and carbohydrate absorption while increasing water and electrolyte absorption
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- Luminal nutrients
- Gastrin, CCK, bombesin, GLP1, and GIP
- Neural influences, including PACAP,VIP, and β-adrenergic agonists stimulate while ACh inhibits secretion
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| Vasoactive Intestinal Polypeptide
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Enteric nervous system
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- Induces relaxation of vascular and nonvascular smooth muscle
- Mediates relaxation of the LES, sphincter of Oddi, and anal sphincter
- Regulates relaxation-associated gut contraction and may be involved with reflex vasodilation in the small intestine
- Inhibits gastric acid secretion
- Stimulates biliary water, bicarbonate, pancreatic enzyme, and intestinal chloride secretion
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- Mechanical stimulation
- Activation of the CNS and PNS
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