Differences between males and females in rates of serotonin synthesis in human brain

Proc Natl Acad Sci U S A. 1997 May 13;94(10):5308-13. doi: 10.1073/pnas.94.10.5308.


Rates of serotonin synthesis were measured in the human brain using positron emission tomography. The sensitivity of the method is indicated by the fact that measurements are possible even after a substantial lowering of synthesis induced by acute tryptophan depletion. Unlike serotonin levels in human brain, which vary greatly in different brain areas, rates of synthesis of the indolamine are rather uniform throughout the brain. The mean rate of synthesis in normal males was found to be 52% higher than in normal females; this marked difference may be a factor relevant to the lower incidence of major unipolar depression in males.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Comment

MeSH terms

  • Adult
  • Analysis of Variance
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Female
  • Humans
  • Kinetics
  • Magnetic Resonance Imaging
  • Male
  • Organ Specificity
  • Serotonin / biosynthesis*
  • Sex Characteristics*
  • Time Factors
  • Tomography, Emission-Computed
  • Tryptophan / blood
  • Tryptophan / deficiency


  • Serotonin
  • Tryptophan