title: Striatal dopamine D1-like receptor binding is unchanged in primary focal dystonia.
abstract: BACKGROUND
  Multiple studies have demonstrated decreases in striatal D2-like (D2, D3) radioligand binding in primary focal dystonias. Although most investigations have focused on D2-specific receptors (D2R), a recent study suggests that the decreased D2-like binding may be due to a D3-specific (D3R) abnormality. However, only limited data exist on the role of D1-specific receptors (D1R) and the D1R-mediated pathways within basal ganglia in dystonia. Metabolic positron emission tomography (PET) data in primary generalized dystonia suggest resting state over activity in the D1R-mediated direct pathway, leading to excessive disinhibition of motor cortical areas. This work investigated whether striatal D1-like receptors are affected in primary focal dystonias.
  
  
  METHODS
  Striatal-specific (caudate and putamen) binding of the D1-like radioligand [(11)C]NNC 112 was measured using PET in 19 patients with primary focal dystonia (cranial, cervical, or arm) and 18 controls.
  
  
  RESULTS
  No statistically significant difference was detected in striatal D1-like binding between the two groups. The study had 91% power to detect a 20% difference, indicating that false-negative results were unlikely.
  
  
  CONCLUSIONS
  Because [(11)C]NNC 112 has high affinity for D1-like receptors, very low affinity for D2-like receptors, and minimal sensitivity to endogenous dopamine levels, we conclude that D1-like receptor binding is not impaired in these primary focal dystonias.
authors.affiliation: Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, USA.
authors.forename: Morvarid
authors.initials: M
authors.lastname: Karimi
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Moerlein
authors.forename: Tom O
authors.initials: TO
authors.lastname: Videen
authors.forename: Yi
authors.initials: Y
authors.lastname: Su
authors.forename: Hubert P
authors.initials: HP
authors.lastname: Flores
authors.forename: Joel S
authors.initials: JS
authors.lastname: Perlmutter
mesh_terms: D000328:Adult; D000368:Aged; D001552:Benzazepines / Q000493:pharmacokinetics; D001572:Benzofurans / Q000493:pharmacokinetics; D003342:Corpus Striatum / Q000000981:diagnostic imaging* / Q000378:metabolism*; D020821:Dystonic Disorders / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D017447:Receptors, Dopamine D1 / Q000378:metabolism*
chemical_list: D001552:Benzazepines; D001572:Benzofurans; D017447:Receptors, Dopamine D1; C077123:NNC 112
keywords: D1 receptor; [11C]NNC 112; focal dystonia; positron emission tomography