title: Effects of rapid tryptophan depletion on brain 5-HT(2) receptors: a PET study.
abstract: BACKGROUND
  The mechanism by which rapid tryptophan depletion (RTD) paradigm induces depressive relapse in recently remitted patients with depression is unknown.
  
  
  OBJECTIVE
  To determine the effects of RTD on brain 5-HT(2) receptors using positron emission tomography (PET) and (18)F-labelled setoperone.
  
  
  METHODS
  Ten healthy women under went two PET scans. Each scan was done 5 h after the ingestion of either a balanced or a tryptophan-deficient amino acid mixture, and the two test sessions were separated by at least 5 days.
  
  
  RESULTS
  The RTD decreased plasma free tryptophan levels significantly but it had no significant effects on mood. Subjects showed a significant decrease in brain 5-HT(2) receptor binding in various cortical regions following the RTD session.
  
  
  CONCLUSIONS
  When taken with the evidence that antidepressant treatment is associated with a decrease in brain 5-HT(2) receptors, these findings suggest that a decrease in 5-HT(2) binding following RTD might be an adaptive response that provides protection against depressive symptoms.
authors.affiliation: Division of Mood Disorders, The University of British Columbia, Canada. yatham@unixg.ubc.ca
authors.forename: L N
authors.initials: LN
authors.lastname: Yatham
authors.forename: P F
authors.initials: PF
authors.lastname: Liddle
authors.forename: I S
authors.initials: IS
authors.lastname: Shiah
authors.forename: R W
authors.initials: RW
authors.lastname: Lam
authors.forename: M J
authors.initials: MJ
authors.lastname: Adam
authors.forename: A P
authors.initials: AP
authors.lastname: Zis
authors.forename: T J
authors.initials: TJ
authors.lastname: Ruth
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D005462:Fluorine Radioisotopes; D006801:Humans; D008875:Middle Aged; D011744:Pyrimidinones; D011985:Receptors, Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists; D014055:Tomography, Emission-Computed / Q000379:methods; D014364:Tryptophan / Q000097:blood / Q000172:deficiency* / Q000502:physiology
chemical_list: D005462:Fluorine Radioisotopes; D011744:Pyrimidinones; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D014364:Tryptophan; C045359:setoperone