Gut + pancreatic + hypothalamic peptide hormones with diverse signaling. Somatostatin (SST) inhibits growth-hormone release + multiple GI secretions; therapeutic analogs (octreotide, lanreotide) for acromegaly + neuroendocrine tumors (carcinoid, VIPoma, glucagonoma) + variceal bleeding. VIP (vasoactive intestinal peptide) → vasodilation + intestinal secretion + bronchodilation. CCK → gallbladder contraction + pancreatic secretion + satiety. Secretin → pancreatic bicarbonate release. Glucagon (α-cell) opposes insulin → hepatic gluconeogenesis + glycogenolysis; clinical glucagon kit for severe hypoglycemia + β-blocker poisoning. Pramlintide is an amylin (IAPP) analog co-secreted with insulin; SC pre-meal injection for type 1 + insulin-treated type 2 diabetes (slows gastric emptying + suppresses glucagon). Retatrutide is a triple GLP-1/GIP/glucagon agonist in late-stage weight-loss trials.
Organ Systems
digestive
endocrine
Pathway Steps
gi-meal-signals → gi-peptide-release — via enteroendocrine cells (K, L, I, S, EC) secrete CCK/GIP/GLP-1/secretin/somatostatin in response to nutrient sensing. Enteroendocrine cells lining the gut sense luminal nutrients and release a suite of hormones — GLP-1, GIP, PYY, CCK, ghrelin, secretin — that regulate digestion, insulin secretion, and appetite. This gut-brain endocrine axis is the target of incretin-based therapies (GLP-1 agonists) for diabetes and obesity.
somatostatin (inhibitor) — SST1-5 (endogenous). native 14-mer + 28-mer; IV infusion for variceal bleed (rare clinical use vs octreotide due to short t½)
secretin (activator) — secretin receptor (SCTR). IV diagnostic for ZE syndrome (paradoxical gastrin rise) + pancreatic function testing; minimal Rx use
cholecystokinin (activator) — CCK-A + CCK-B. gallbladder contraction + pancreatic secretion + central satiety; IV diagnostic only