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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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