title: L-cysteine suppresses ghrelin and reduces appetite in rodents and humans.
abstract: BACKGROUND
  High-protein diets promote weight loss and subsequent weight maintenance, but are difficult to adhere to. The mechanisms by which protein exerts these effects remain unclear. However, the amino acids produced by protein digestion may have a role in driving protein-induced satiety.
  
  
  METHODS
  We tested the effects of a range of amino acids on food intake in rodents and identified l-cysteine as the most anorexigenic. Using rodents we further studied the effect of l-cysteine on food intake, behaviour and energy expenditure. We proceeded to investigate its effect on neuronal activation in the hypothalamus and brainstem before investigating its effect on gastric emptying and gut hormone release. The effect of l-cysteine on appetite scores and gut hormone release was then investigated in humans.
  
  
  RESULTS
  l-Cysteine dose-dependently decreased food intake in both rats and mice following oral gavage and intraperitoneal administration. This effect did not appear to be secondary to behavioural or aversive side effects. l-Cysteine increased neuronal activation in the area postrema and delayed gastric emptying. It suppressed plasma acyl ghrelin levels and did not reduce food intake in transgenic ghrelin-overexpressing mice. Repeated l-cysteine administration decreased food intake in rats and obese mice. l-Cysteine reduced hunger and plasma acyl ghrelin levels in humans.
  
  
  CONCLUSIONS
  Further work is required to determine the chronic effect of l-cysteine in rodents and humans on appetite and body weight, and whether l-cysteine contributes towards protein-induced satiety.
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: A K
authors.initials: AK
authors.lastname: McGavigan
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: H C
authors.initials: HC
authors.lastname: O'Hara
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Amin
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Kinsey-Jones
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: E
authors.initials: E
authors.lastname: Spreckley
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Alamshah
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Agahi
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: K
authors.initials: K
authors.lastname: Banks
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: France
authors.affiliation: AstraZeneca R&D, Mölndal, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Hyberg
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Wong
authors.affiliation: 1] Department of Investigative Medicine, Imperial College London, London, UK [2] Division of Diabetes & Nutritional Sciences, King's College London, London, UK.
authors.forename: G A
authors.initials: GA
authors.lastname: Bewick
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: J V
authors.initials: JV
authors.lastname: Gardiner
authors.affiliation: 1] AstraZeneca R&D, Mölndal, Sweden [2] NextRx, Gothenburg, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Lehmann
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: N M
authors.initials: NM
authors.lastname: Martin
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Ghatei
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: S R
authors.initials: SR
authors.lastname: Bloom
authors.affiliation: Department of Investigative Medicine, Imperial College London, London, UK.
authors.forename: K G
authors.initials: KG
authors.lastname: Murphy
mesh_terms: D000328:Adult; D000818:Animals; D001066:Appetite / Q000187:drug effects*; D001067:Appetite Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D003545:Cysteine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D005260:Female; D005768:Gastrointestinal Hormones / Q000378:metabolism; D054439:Ghrelin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger; D051381:Rats; D017208:Rats, Wistar; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000378:metabolism; D012527:Satiation
chemical_list: D001067:Appetite Depressants; D005768:Gastrointestinal Hormones; D054439:Ghrelin; D012333:RNA, Messenger; D011964:Receptors, Gastrointestinal Hormone; D018013:Receptors, Neuropeptide; D003545:Cysteine