Satiation signals. Cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) are signal molecules that induce feelings of satiety in the brain. CCK is secreted by specialized cells of the small intestine in response to a meal and activates satiation pathways in the brain. GLP-1, secreted by L cells in the intestine, also activates satiation pathways in the brain and potentiates insulin action in the pancreas.

[Information from S. C. Wood, Cell Metab. 9:489–498, 2009, Fig. 1.]