Examining serotonin function: a modified technique for rapid tryptophan depletion.
Tryptophan (TRP) depletion was used to study serotonin because the ratio of TRP to large neutral amino acids (TRP/LNAA) determines the quantity of TRP that enters the brain. Because TRP is not universally available, a modified technique of TRP depletion was developed where a 1/4 strength preparation of an amino acid mixture (AAM) replaces TRP as the placebo. Seven healthy subjects could not differentiate between the preparations in this double-blind, placebo-controlled study. Urinary 6-hydroxymelatonin sulfate (6-MS) was monitored as a biochemical marker of serotonin. The TRP/LNAA ratio (GG = 0.001) and 6-MS secretion (GG = 0.024) were decreased, but placebo TRP levels (GG = 0.062) were not altered significantly. This modified technique facilitates the use of TRP depletion in clinical research.
Department of Psychiatry, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
L E
LE
Krahn
P Y
PY
Lu
G
G
Klee
P R
PR
Delgado
S C
SC
Lin
R C
RC
Zimmermann
D000328:Adult; D000596:Amino Acids / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*
D000596:Amino Acids; D012701:Serotonin; D014364:Tryptophan