Biological Controls of Food Intake

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Biological Controls of Food Intake
Cholecystokinin (CCK) Leptin
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How is food intake studied in the lab???
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How is food intake studied in the lab???
Food intake meal size x meal number
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Neuropeptides that Control Food Intake

• Cholecystokinin (CCK) Animal Research
• polypeptide
• synthesized in the duodenum
• secreted in response to nutrients in the small
  intestine
• binds to peripheral CCK-1 receptors on the
  vagus nerve
• increases neuronal activation within a specific
  brain circuit
• decreases food intake by decreasing meal size
• decreases gastric emptying
• produces no aversive side effects after low
  doses
• CCK antagonist (devazepide) increases food
  intake by increasing meal size

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• Cholecystokinin Human Research
• released from the duodenum during a meal
• activates a neural satiety circuit
• decreases gastric emptying
• promotes a feeling of satiety
• no aversive side effects

• Predictions About CCK and Anorexia Nervosa ???
• CCK secretion is normal or elevated
• smaller meal size - satiety is reached more
  quickly
• delays gastric emptying more food in the
  stomach discomfort
• these features make it easier to engage in
  chronic caloric restriction

• Predictions About CCK and Bulimia ???
• CCK secretion is decreased
• larger meal size takes longer to feel satiated
• increased gastric emptying makes more room for
  food in the stomach
• these features make it easier to engage in
  bingeing behavior

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• Leptin Animal Research
• hormone
• synthesized in white adipose tissue
• secreted in proportion to body adiposity
• binds to leptin receptors in the brain
• decreases food intake by decreasing meal size
• produces no aversive side effects after low
  doses

leptin
leptin
Brain
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• Leptin in Healthy Individuals
• functions as a long term regulator of body
  adiposity
• release is not affected by individual meals
• chronic leptin treatment reduces body weight in
  a subset of obese individuals
• some side effects

• Predictions About Leptin and Anorexia Nervosa ???
• leptin secretion is reduced
• initially, this would stimulate appetite
  behavioral override?
• likely contributes to the amenorrhea

• Predictions About Leptin and Bulimia ???
• no clear association