Table 3

Summary of the action of selected gastrointestinal hormones, insulin and leptin and how they are altered in obesity 9

Gut hormone Gastrointestinal site of secretion Action on gastrointestinal system Effect on appetite Changes in obesity
GhrelinX/A-cells in gastric fundusIncreases gastric motilityIncreases appetiteReduced pre-prandial peak levels and reduced postprandial suppression
Peptide YY3-36 L-cells in distal intestineInhibits gallbladder secretions, inhibits gastric emptying, inhibits pancreatic secretions, enterogastrone effect.Decreases appetiteReduced fasting and postprandial secretion
Glucagon-like peptide-1L-cells in distal intestineInhibits gastric emptying, inhibits gastric secretions, promotes pancreatic beta-cell growth, incretin effect.Decreases appetiteReduced postprandial secretion
OxyntomodulinL-cells in distal intestineInhibits gastric secretions, inhibits gastric emptying, incretin effect.Decreases appetite
CholecystokininI cells in small intestine, co-localises with PYY in L-cells of distal intestinePromotes gallbladder contraction, increases pancreatic secretions, inhibits gastric secretions, inhibits gastric emptying.Decreases appetiteNot implicated
Peripheral hormone Site of secretion Effect on appetite Changes in obesity
InsulinPancreas (beta-cells)Decreases appetiteHyperinsulinaemia, insulin resistance
LeptinAdipocytesDecreases appetiteHyperleptinaemia, leptin resistance