title: The role of medial hypothalamic serotonin in the suppression of feeding in a rat model of colitis.
abstract: OBJECTIVE
  Experimental colitis is associated with anorexia that is attenuated by treatment with an interleukin (IL)-1 receptor antagonist. Serotonin (5-hydroxytryptamine [5-HT]) is a potent inhibitor of feeding, and its release from the hypothalamus is stimulated by IL-1. We have tested the hypotheses that anorexia associated with experimental colitis results from increased activity of hypothalamic 5-HT neurons and that the increase in activity occurs secondary to an increase in availability of tryptophan, the precursor of 5-HT.
  
  
  METHODS
  In vivo 5-HT release and regional hypothalamic 5-HT and tryptophan concentrations were measured in rats with 2,4,6,-trinitrobenzene sulfonic acid (TNBS)-induced colitis, healthy controls, and animals pair-fed to match the food intake of the colitic group. Food intake in the colitic group was assessed after depletion of brain 5-HT by p-chlorophenylalanine (PCPA).
  
  
  RESULTS
  In the colitic group, release of 5-HT from the hypothalamic paraventricular nucleus (PVN) was 3-fold (P = 0.01) and 14-fold (P < 0.001) higher than in control and pair-fed groups, respectively. Concentrations of tryptophan were similar in each group in all hypothalamic regions. Food intake was significantly increased in the colitic group after PCPA treatment but was not restored to control values.
  
  
  CONCLUSIONS
  In animals with TNBS-induced colitis, 5-HT release from the PVN is increased. The increase in food intake after depletion of brain 5-HT suggests that hypothalamic 5-HT contributes to anorexia but is not the only mediator. Increased 5-HT release in the colitic group was not driven by increased precursor availability.
authors.affiliation: Digestive Diseases Research Centre, England. a.b.ballinger@mds.qmw.ac
authors.forename: A
authors.initials: A
authors.lastname: Ballinger
authors.forename: T
authors.initials: T
authors.lastname: El-Haj
authors.forename: D
authors.initials: D
authors.lastname: Perrett
authors.forename: J
authors.initials: J
authors.lastname: Turvill
authors.forename: O
authors.initials: O
authors.lastname: Obeid
authors.forename: S
authors.initials: S
authors.lastname: Dryden
authors.forename: G
authors.initials: G
authors.lastname: Williams
authors.forename: M J
authors.initials: MJ
authors.lastname: Farthing
mesh_terms: D000596:Amino Acids / Q000097:blood; D000818:Animals; D000855:Anorexia / Q000209:etiology*; D003092:Colitis / Q000097:blood / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D010134:Fenclonine / Q000494:pharmacology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D007033:Hypothalamus, Middle / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D014018:Tissue Distribution; D014364:Tryptophan / Q000097:blood / Q000378:metabolism
chemical_list: D000596:Amino Acids; D012702:Serotonin Antagonists; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D010134:Fenclonine