title: Cerebral serotonin transporter asymmetry in females, males and male-to-female transsexuals measured by PET in vivo.
abstract: The serotonergic system modulates brain functions that are considered to underlie affective states, emotion and cognition. Several lines of evidence point towards a strong lateralization of these mental processes, which indicates similar asymmetries in associated neurotransmitter systems. Here, our aim was to investigate a potential asymmetry of the serotonin transporter distribution using positron emission tomography and the radioligand [(11)C]DASB in vivo. As brain asymmetries may differ between sexes, we further aimed to compare serotonin transporter asymmetry between females, males and male-to-female (MtF) transsexuals whose brains are considered to be partly feminized. Voxel-wise analysis of serotonin transporter binding in all groups showed both strong left and rightward asymmetries in several cortical and subcortical structures including temporal and frontal cortices, anterior cingulate, hippocampus, caudate and thalamus. Further, male controls showed a rightward asymmetry in the midcingulate cortex, which was absent in females and MtF transsexuals. The present data support the notion of a lateralized serotonergic system, which is in line with previous findings of asymmetric serotonin-1A receptor distributions, extracellular serotonin concentrations, serotonin turnover and uptake. The absence of serotonin transporter asymmetry in the midcingulate in MtF transsexuals may be attributed to an absence of brain masculinization in this region.
authors.affiliation: Functional, Molecular and Translational Neuroimaging Lab, Department of Psychiatry and Psychotherapy, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Georg S
authors.initials: GS
authors.lastname: Kranz
authors.forename: Andreas
authors.initials: A
authors.lastname: Hahn
authors.forename: Pia
authors.initials: P
authors.lastname: Baldinger
authors.forename: Daniela
authors.initials: D
authors.lastname: Haeusler
authors.forename: Cecile
authors.initials: C
authors.lastname: Philippe
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kaufmann
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wadsak
authors.forename: Markus
authors.initials: M
authors.lastname: Savli
authors.forename: Anna
authors.initials: A
authors.lastname: Hoeflich
authors.forename: Christoph
authors.initials: C
authors.lastname: Kraus
authors.forename: Thomas
authors.initials: T
authors.lastname: Vanicek
authors.forename: Markus
authors.initials: M
authors.lastname: Mitterhauser
authors.forename: Siegfried
authors.initials: S
authors.lastname: Kasper
authors.forename: Rupert
authors.initials: R
authors.lastname: Lanzenberger
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000000981:diagnostic imaging*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011569:Psychiatric Status Rating Scales; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D014189:Transsexualism / Q000000981:diagnostic imaging* / Q000473:pathology*
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins