Table 5.
Illustrative Gastrointestinal Hormones. Anti-obesity drug development often involves analogue adaptations of hormones and other factors applicable to gastrointestinal responses to food intake [[128], [129], [130], [131], [132], [133], [134], [135], [136], [137], [138]].
| Where secreted | Gastrointestinal hormone | Effect of hormone on eating behavior | Effect of eating on hormone secretion | Notes: | Effect of gastric by-pass and sleeve gastrectomy |
|---|---|---|---|---|---|
| Stomach | Ghrelin (secreted by P/D1 cells) | ↑ Hunger | ↓ | ↑With fasting ↑Gastric emptying/ ↑Growth Hormone |
Ghrelin is likely to decrease with sleeve gastrectomy (not so with gastric bypass) |
| Gastrin (secreted by G cells in antrum) | ↓ Hunger | ↑ | ↑ Hydrochloric acid and pepsinogen | ↓Gastric bypass -/↑ Sleeve |
|
| Pancreasa | Insulin (secreted by pancreatic beta cells) | ↓ Hunger | ↑ | ↑Hunger with hypoglycemia ↑Glucose transporter 4 in adipose tissue/muscle, glycogenesis, lipoprotein lipase activity, lipogenesis |
↓ Insulin resistance/fasting insulin ↑ Insulin sensitivity/insulin responsiveness |
| Glucagon (secreted by pancreatic alpha cells) | ↓ Hunger | ↓ | ↑Glycogen to glucose ↑Postprandial glucagon in patients with type 2 diabetes mellitus (if glucagon not suppressed) |
Variable | |
| Pancreatic polypeptide (PP) [secreted by PP (F) cells] | ↓ Hunger | ↑ | ↓ Pancreatic exocrine secretion | Variable | |
| Amylin (secreted by pancreatic beta cells) | ↓ Hunger | ↑ | ↓ Gastric emptying, glucagon | - ↓ | |
| Somatostatin (secreted by D cells pylori antrum, duodenum, and pancreatic islets) | ↓ Hunger | ↑ | ↓ Growth hormone, gastrin, hydrochloric acid (HCl), secretin, cholecystokinin (CCK), insulin, glucagon | - ↑ | |
| Small intestine (mainly duodenum and jejunum) | Cholecystokinin (CCK) (secreted by I-cells) |
↓ Hunger | ↑ | ↑ Gall bladder contractility and bile, pancreatic enzymes; ↓ Gastric emptying |
↑ postprandial |
| Secretin (secreted by S cells) | ↓ Hunger (?) | ↑ | ↑Pancreatic bicarbonate and bile ↓ Intestinal motility & gastric acid |
Variable | |
| Glucose-dependent insulinotropic peptide (GIP; also known as Gastric Inhibitory Peptide and is secreted by K cells) | ↓ Hunger (?) | ↑ | ↑Insulin ↑Glucagon postprandial |
Variable | |
| Motilin (secreted by M or Mo cells) | ↓ Hunger | ↓ (↑ with fasting) | ↑ Gastric motility, interdigestive migratory contractions (borborygmi) | ? | |
| Ileum and/or large intestine | Fibroblast growth factor (FGF) 19 [FGF 21 is produced by the liver] (secreted by ileal cells and regulated by farnesoid X receptors - FXR) | ↓ Hunger | ↑ | ↓ Bile acids, glucose production ↑Insulin sensitivity, glycogen synthesis |
↑ |
| Glucagon like peptide-1 (secreted by ileum/colon L-cells) | ↓ Hunger | ↑ | ↑Insulin ↓Glucagon, gastric emptying |
↑ | |
| Glucagon like peptide-2 (secreted by ileum/colon L-cells) | ↓ Hunger | ↑ | ↑Glucose metabolism, intestinal mucosal growth, increases absorptive surface, epithelial brush-border nutrient transporters and digestive enzymes, intestinal blood flow, postprandial chylomicron secretion ↓ Gastrointestinal motility |
↑ | |
| Oxyntomodulin (secreted by ileum/colon L-cells) | ↓ Hunger | ↑ | ↑ GLP-1 and glucagon receptor activity ↓ Gastric acid and gastric emptying |
↑ Gastric bypass - Sleeve gastrectomy |
|
| Peptide YY (secreted by ileum/colon L-cells) | ↓ Hunger | ↑ | ↓ Gall bladder and pancreatic secretions, gastric emptying | ↑ |
a
Pancreatic epsilon cells produce ghrelin, with a potential increase release of pancreatic ghrelin after sleeve gastrectomy [127].