fat in response to physical or psychogenic stress (Kuo et al. 2007 ). High-fat,
high-sugar diets stimulate the release of NPY contributing to increases in the vis-
ceral adipose depot (Kuo et al. 2007 ). The complex interactions of adipose secre-
tions with both regulatory secretions from other peripheral organs and the brain
pose difficulties in elucidating the roles of these biomarkers. The digestive endo-
crine system summarized in Table10.4includes nearly three dozen peptides and
neuropeptides synthesized and secreted by the stomach, small intestine, colon,
pancreas, and brain. These influence gut motility, peripheral metabolism, other gut
Table 10.4 Gut–brain biomarkers regulating appetite and food intake and central nervous system
sites of action
Hormone/peptide Site of
synthesis
Site of action (HYP
hypothalamus,HB
hindbrain,Vvagus nerve)
Functions
Ghrelin Stomach HYP, HB, V Stimulates feeding
Leptin Stomach HYP, HB, V Inhibits feeding
Gastrin-releasing
peptide (GRP)
Stomach HB, V Delays gastric emptying, reduces
food intake
Neuromedin-B
(NMB)
Stomach HB, V Secreted in response to fat
ingestion, increases satiation
Cholecystokinin
(CCK)
Small
intestine
HYP, HB, V Terminates feeding
Apolipoprotein
A-IV (APO AIV)
Small
intestine
HYP, V Secreted in response to fat
absorption
Glucagon-like
peptide-1 (GLP1)
Small
intestine,
colon
HYP, HB, V Delays gastric emptying
Oxyntomodulin Small
intestine,
colon
HYP Increases satiation, reduces food
intake
Peptide YY
(PYY)
Small
intestine,
colon
HYP, V Delays gastric emptying
Amylin Pancreas HYP, HB Inhibits gastric emptying, gastric
acid, and glucagon secretion,
reduces food intake
Enterostatin Pancreas V Secreted in response to fat
ingestion
Glucagon Pancreas V Increases satiation and reduces
food intake
Insulin Pancreas HYP Increases satiety, reduces food
intake size
Pancreatic
polypeptide (PP)
Pancreas HB, V Both increases and decreases
food intake, depending in site of
action
Power and Schulkin ( 2009 ), after Table 7.3 Gut–Brain peptides involved in regulating food intake,
p. 174
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