title: No evidence for in vivo regulation of midbrain serotonin transporter availability by serotonin transporter promoter gene polymorphism.
abstract: BACKGROUND
  A polymorphism in the serotonin transporter promoter gene region (5-HTTLPR) has been shown to influence the quantity of serotonin transporter expressed in human cell lines: the 5-HTTLPR short allele (s) has been associated with reduced 5-HTT expression when compared to cells carrying the 5-HTTLPR long allele (l). We performed a single photon emission computed tomography (SPECT) study using the ligand [(123)I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)tropane ([(123)I]-beta-CIT) to measure 5-HTT availability in 16 healthy subjects genotyped for 5-HTTLPR.
  
  
  METHODS
  SPECT scans were performed 24 hours after tracer injection, regions of interest anatomically corresponding to the thalamus-hypothalamus and mesencephalon-pons areas were compared to the binding in the cerebellum, representing the nondisplaceable [(123)I]-beta-CIT-binding (results expressed as target activity minus cerebellum activity/cerebellum activity). DNA from peripheral nuclear blood cells was genotyped for 5-HTTLPR using standard polymerase chain reaction methods.
  
  
  RESULTS
  Specific binding ratios in the thalamus-hypothalamus were 2.65 +/- 0.4 in subjects with the l/l genotype (n = 3), 2.76 +/- 0.5 in subjects with the l/s genotype (n = 9), and 2.77 +/- 0.4 in subjects with the s/s genotype (n = 4). Binding ratios in the mesencephalon-pons were 1.43 +/- 0.3 (l/l; n = 3), 1.37 +/- 0.3 (l/s; n = 9), and 1.28 +/- 0.3 (s/s; n = 4). None of these differences was statistically significant.
  
  
  CONCLUSIONS
  Our data provide no evidence for in vivo functional regulation of 5-HTT availability by 5-HTTLPR in the thalamus-hypothalamus and mesencephalon-pons of healthy subjects.
authors.affiliation: Department of General Psychiatry, Vienna University, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Willeit
authors.forename: J
authors.initials: J
authors.lastname: Stastny
authors.forename: W
authors.initials: W
authors.lastname: Pirker
authors.forename: N
authors.initials: N
authors.lastname: Praschak-Rieder
authors.forename: A
authors.initials: A
authors.lastname: Neumeister
authors.forename: S
authors.initials: S
authors.lastname: Asenbaum
authors.forename: J
authors.initials: J
authors.lastname: Tauscher
authors.forename: K
authors.initials: K
authors.lastname: Fuchs
authors.forename: W
authors.initials: W
authors.lastname: Sieghart
authors.forename: K
authors.initials: K
authors.lastname: Hornik
authors.forename: H N
authors.initials: HN
authors.lastname: Aschauer
authors.forename: T
authors.initials: T
authors.lastname: Brücke
authors.forename: S
authors.initials: S
authors.lastname: Kasper
mesh_terms: D000328:Adult; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000235:genetics*; D006801:Humans; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D008636:Mesencephalon / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D013788:Thalamus / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin