title: Ventral striatum binding of a dopamine D2/3 receptor agonist but not antagonist predicts normal body mass index.
abstract: BACKGROUND
  Positron emission tomography research has shown that dopamine D2/3 receptor (D2/3R) availability is negatively correlated with body mass index (BMI) in obese but not in healthy subjects. However, previous positron emission tomography studies have not looked specifically at the ventral striatum (VS), which plays an important role in motivation and feeding. Furthermore, these studies have only used antagonist radiotracers. Normal-weight rats given free access to high-fat diets demonstrate behavioral sensitization to D2/3R agonists but not to antagonists. Sensitization is associated with increased D2/3R affinity, which affects binding of agonists but not antagonists.
  
  
  METHODS
  We examined the association between BMI within the nonobese range (18.6-27.8) and D2/3R availability in the VS with the use of the agonist radiotracer [(11)C]-(+)-PHNO (n = 26) and the antagonist [(11)C]-raclopride (n = 35) in healthy humans.
  
  
  RESULTS
  In the VS, we found a positive correlation between BMI and [(11)C]-(+)-PHNO binding but no relationship with [(11)C]-raclopride binding. Secondary analyses revealed no relationship between BMI and binding in the dorsal striatum with either radiotracer.
  
  
  CONCLUSIONS
  We propose that in nonobese individuals, higher BMI may be associated with increased D2R affinity in the VS. This increased affinity may potentiate the incentive salience of food cues and counteract the effects of satiety cues, thereby increasing feeding.
authors.affiliation: Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Fernando
authors.initials: F
authors.lastname: Caravaggio
authors.affiliation: Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sofia
authors.initials: S
authors.lastname: Raitsin
authors.affiliation: Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Philip
authors.initials: P
authors.lastname: Gerretsen
authors.affiliation: Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakajima
authors.affiliation: Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Alan
authors.initials: A
authors.lastname: Wilson
authors.affiliation: Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada. Electronic address: ariel.graff@camh.ca.
authors.forename: Ariel
authors.initials: A
authors.lastname: Graff-Guerrero
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002250:Carbon Radioisotopes; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020891:Raclopride; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D050637:Receptors, Dopamine D3 / Q000378:metabolism*; D066328:Ventral Striatum / Q000000981:diagnostic imaging* / Q000378:metabolism*; D055815:Young Adult
chemical_list: D002250:Carbon Radioisotopes; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D020891:Raclopride
keywords: Body mass index; Dopamine D(2) receptor; Food addiction; Obesity; PET; Ventral striatum
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