title: Regional distribution of serotonin transporter protein in postmortem human brain: is the cerebellum a SERT-free brain region?
abstract: BACKGROUND
  The primary approach in assessing the status of brain serotonin neurons in human conditions such as major depression and exposure to the illicit drug ecstasy has been the use of neuroimaging procedures involving radiotracers that bind to the serotonin transporter (SERT). However, there has been no consistency in the selection of a "SERT-free" reference region for the estimation of free and nonspecific binding, as occipital cortex, cerebellum and white matter have all been employed.
  
  
  OBJECTIVE
  To identify areas of human brain that might have very low SERT levels, we measured, by a semiquantitative Western blotting procedure, SERT protein immunoreactivity throughout the postmortem brain of seven normal adult subjects.
  
  
  RESULTS
  Serotonin transporter could be quantitated in all examined brain areas. However, the SERT concentration in cerebellar cortex and white matter were only at trace values, being approximately 20% of average cerebral cortex and 5% of average striatum values.
  
  
  CONCLUSIONS
  Although none of the examined brain areas are completely free of SERT, human cerebellar cortex has low SERT binding as compared to other examined brain regions, with the exception of white matter. Since the cerebellar cortical SERT binding is not zero, this region will not be a suitable reference region for SERT radioligands with very low free and nonspecific binding. For SERT radioligands with reasonably high free and nonspecific binding, the cerebellar cortex should be a useful reference region, provided other necessary radioligand assumptions are met.
authors.affiliation: Human Neurochemical Pathology Laboratory, Centre for Addiction and Mental Health, Toronto, ON, Canada M5T 1R8. Stephen_Kish@CAMH.net
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Kish
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Furukawa
authors.forename: Li-Jan
authors.initials: LJ
authors.lastname: Chang
authors.forename: Junchao
authors.initials: J
authors.lastname: Tong
authors.forename: Nathalie
authors.initials: N
authors.lastname: Ginovart
authors.forename: Alan
authors.initials: A
authors.lastname: Wilson
authors.forename: Sylvain
authors.initials: S
authors.lastname: Houle
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Meyer
mesh_terms: D015153:Blotting, Western / Q000379:methods*; D001921:Brain / Q000378:metabolism*; D002102:Cadaver; D002531:Cerebellum / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D012016:Reference Values; D050486:Serotonin Plasma Membrane Transport Proteins; D014018:Tissue Distribution
chemical_list: D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins