title: Acute tryptophan depletion alters gastrointestinal and anxiety symptoms in irritable bowel syndrome.
abstract: OBJECTIVE
  To assess the effect of acute changes in serotonin (5-HT) synthesis using the acute tryptophan depletion (ATD) paradigm on gastrointestinal (GI) and mood symptoms in irritable bowel syndrome (IBS).
  
  
  METHODS
  In a randomized double-blind crossover study, 29 subjects (18 patients with ROME II defined IBS and 11 age-matched controls) were studied under ATD and acute tryptophan increase (ATI) conditions. GI symptoms, mood and anxiety ratings, as well as plasma tryptophan concentrations were measured.
  
  
  RESULTS
  Total (and free) plasma tryptophan concentrations decreased on the ATD day in patients (73%[82%]) and controls (73%[80%]), and increased on the ATI day in patients (59%[143%]) and controls (61%[381%]). Compared with the ATD day, IBS patients reported more GI symptoms on the ATI day at +210 (p < 0.001) and at +270 (p < 0.05) min post drink. IBS patients also reported less anxiety on the ATI day compared with the ATD day at +270 min (p < 0.001). ATD and ATI did not affect these ratings in control participants. IBS patients had a lower mood compared with controls (p < 0.05), but this did not differ between the ATI and ATD days in either group.
  
  
  CONCLUSIONS
  IBS patients' GI and anxiety responses to changes in tryptophan load differ from controls. This suggests a difference in serotonergic functioning between these two groups and provides evidence to support the hypothesis that 5-HT dysfunction is involved in IBS.
authors.affiliation: Clinical Science at South Bristol, University of Bristol, Bristol, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Shufflebotham
authors.forename: Sean
authors.initials: S
authors.lastname: Hood
authors.forename: Julie
authors.initials: J
authors.lastname: Hendry
authors.forename: Dana A
authors.initials: DA
authors.lastname: Hince
authors.forename: Kelly
authors.initials: K
authors.lastname: Morris
authors.forename: David
authors.initials: D
authors.lastname: Nutt
authors.forename: Chris
authors.initials: C
authors.lastname: Probert
authors.forename: John
authors.initials: J
authors.lastname: Potokar
mesh_terms: D000328:Adult; D000339:Affect; D001007:Anxiety; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D041981:Gastrointestinal Tract / Q000503:physiopathology*; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000378:metabolism* / Q000503:physiopathology / Q000523:psychology; D008297:Male; D012701:Serotonin / Q000096:biosynthesis; D014364:Tryptophan / Q000097:blood / Q000172:deficiency*
chemical_list: D012701:Serotonin; D014364:Tryptophan