L7 - CCK

  • Created by: BKW
  • Created on: 09-01-20 11:07
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  • L7 - Cholecytokinin CCK
    • What is it?
      • A pancreatic Enzyme, a neuropeptide released in gut after eating as a response to food, its used for ST appetite regulation
      • It inhibits food intake
        • Gibbs, Young&Smith 1973 found it vvv food intake in fasted rodents who had been injected
          • Ballinger et al did this on 6 healthy pps with IV infusions of cck8 - food intake significantly vvv during cck conditions and plasma concentration ^^^ immediately before meal
    • Verbalis&Stricker argue CCK injections cause nausea and sickness which is why pps don't want to eat
      • In their study they show cck ^^^ plasma levels of  oxytocin which is comparable to nausea promoting chemicals used in taste aversion study
      • CA - CCK specific receptors in brain and gut discovered
        • Certain drugs act as CCK receptor antagonists eg loxiglumide ^^^ food intake
      • rats unresponsive to cck
    • Conditioned taste Aversion
      • can be used on humans and animals
      • injected with drug such as LiCl and if it makes them feel ill they learn to associate with taste not the drug. so if something tastes similar they wont eat
        • to counter claims cck just makes people nauseas several studies have shown CCK and LiCl have different effects
          • Ervin&Teeter - IP infusions of CCK&LiCl at increasing doses - All doses of LiCl unduces strong aversion where as only highest dose of CCK caused mild aversion. All doses of CCK vvv food intake only high dose of LiCl vvv food intake but rats were also distressed
          • West et al IP infusion of CCK&LiCl to rats at the start &throughout each meal for 5 days - found LiCl vvv feeding frequency but not size or duration of meals whereas CCK vvv meal size and duration but ^^^ frequency to compensate for smaller meals
    • CCK receptors
      • CCKa
        • primary target to mediate satiety
        • Located in - distal stomach & ending of vagal affrent fibres
      • CCKb
        • Located in hypothalamus
        • their role is unclear
      • Menton et al 4 female pps gatric balooon infused with CCK or saline - CCK = fullness ratings ^^^ so did fullness and hunger vvv in relation to gastric pressure. gastric contractions abolished with cck
    • OLEFT Rats
      • mutation in CCKa receptor gene
      • no protein expression
      • insensitive to added CCK
      • Average meaal size 50%^^^ so heavily obese


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