Differential Brain Activation in Exclusively Homosexual and Heterosexual Men Produced by the Selective Serotonin Reuptake Inhibitor, Fluoxetine

Brain Res. 2004 Oct 22;1024(1-2):251-4. doi: 10.1016/j.brainres.2004.07.070.


A number of studies have shown a relationship between "sexual orientation" and size of various brain nuclei. We hypothesized that neurotransmitter differences might parallel neuroanatomical differences in the hypothalamus. We administered 40 mg of fluoxetine as a challenge to the serotonergic systems of exclusively homosexual and exclusively heterosexual men and measured cerebral metabolic changes with fluorodeoxyglucose positron emission tomography (FDG-PET). The metabolic differences we observed might reflect underlying neurochemical differences between homosexual and heterosexual men.

Publication types

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

MeSH terms

  • Adult
  • Brain / drug effects
  • Brain / metabolism*
  • Fluoxetine / pharmacology*
  • Heterosexuality / drug effects
  • Heterosexuality / physiology*
  • Homosexuality, Male*
  • Humans
  • Male
  • Positron-Emission Tomography
  • Serotonin Uptake Inhibitors / pharmacology*


  • Serotonin Uptake Inhibitors
  • Fluoxetine