title: Reduction of brain dopamine concentration with dietary tyrosine plus phenylalanine depletion: an [11C]raclopride PET study.
abstract: OBJECTIVE
  Extracellular dopamine concentrations were estimated through measurement of [(11)C]raclopride binding with positron emission tomography after dietary manipulation of the dopamine precursors tyrosine and phenylalanine.
  
  
  METHODS
  Healthy male subjects were scanned on two occasions: once after receiving a balanced amino acid drink and once after receiving a drink mixture from which tyrosine and phenylalanine were omitted.
  
  
  RESULTS
  Dietary tyrosine and phenylalanine depletion increased [(11)C]raclopride binding in the striatum by a mean of 6%. The change in [(11)C]raclopride binding correlated significantly with the fall in the ratio of tyrosine and phenylalanine to large neutral amino acids.
  
  
  CONCLUSIONS
  This is the first demonstration of an effect of a dietary manipulation on brain dopamine release in humans. This result provides support for the further investigation of the role of dietary manipulations in the treatment of neuropsychiatric disorders.
mesh_terms: D000328:Adult; D001628:Beverages; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002250:Carbon Radioisotopes; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010649:Phenylalanine / Q000008:administration & dosage*; D020891:Raclopride / Q000378:metabolism; D012016:Reference Values; D014055:Tomography, Emission-Computed; D014443:Tyrosine / Q000008:administration & dosage*
chemical_list: D002250:Carbon Radioisotopes; D014443:Tyrosine; D020891:Raclopride; D010649:Phenylalanine; D004298:Dopamine