title: Striatal dopamine D2 receptors in medication-naive patients with major depressive disorder as assessed with [11C]raclopride PET.
abstract: BACKGROUND
  Among other monoamine neurotransmitters, dopamine is implicated in the pathophysiology of major depression. Experimental studies suggest the involvement of the mesolimbic dopamine system in the mechanism of action of antidepressant drugs. Previous in vivo imaging studies have studied striatal dopamine D2 receptor availability in depression but the results are equivocal thus far.
  
  
  OBJECTIVE
  To study the striatal and thalamic dopamine D2 receptor availability in drug-naive patients with major depression was the aim of this study.
  
  
  METHODS
  Caudate, putamen, and thalamic dopamine D2 receptor availability was estimated using positron emission tomography and [11C]raclopride in 25 treatment-seeking drug-free patients (of whom 24 were drug-naive) with major depression (primary care patients) as well as in 19 demographically similar healthy control subjects. Receptor availability was expressed as the binding potential (BP ND), and analyses were carried out based on both regional and voxel-level BP ND estimates.
  
  
  RESULTS
  No statistically significant differences in [11C]raclopride BP ND were observed between the groups either in the caudate nucleus (+1.7%, CI -4.8% to +8.3%), putamen (-1.0%, CI -7.2% to 5.1%), thalamus (-2.4%, CI -8.7% to 4.0%), or ventral striatum (-3.8%, CI -9.3% to +1.6%). In the patients, depressive symptoms were not associated with [11C]raclopride BP ND in any region.
  
  
  CONCLUSIONS
  The findings in this sample of treatment-seeking, drug-naive and predominantly first-episode patients with major depression do not support the involvement of striatal dopamine D2 receptors in the pathophysiology of the illness, but do not exclude the potential importance of dopaminergic mechanisms in antidepressant drug action.
authors.affiliation: Department of Psychiatry, University of Turku, Turku, Finland. jueshi@utu.fi
authors.forename: Jussi
authors.initials: J
authors.lastname: Hirvonen
authors.forename: Hasse
authors.initials: H
authors.lastname: Karlsson
authors.forename: Jaana
authors.initials: J
authors.lastname: Kajander
authors.forename: Juha
authors.initials: J
authors.lastname: Markkula
authors.forename: Helena
authors.initials: H
authors.lastname: Rasi-Hakala
authors.forename: Kjell
authors.initials: K
authors.lastname: Någren
authors.forename: Jouko K
authors.initials: JK
authors.lastname: Salminen
authors.forename: Jarmo
authors.initials: J
authors.lastname: Hietala
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D003342:Corpus Striatum / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003865:Major Depressive Disorder / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology; D018492:Dopamine Antagonists / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D020891:Raclopride / Q000493:pharmacokinetics; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012016:Reference Values; D013788:Thalamus / Q000000981:diagnostic imaging* / Q000503:physiopathology
chemical_list: D002250:Carbon Radioisotopes; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D020891:Raclopride