Occupancy of brain dopamine D3 receptors and drug craving: a translational approach

Neuropsychopharmacology. 2013 Jan;38(2):302-12. doi: 10.1038/npp.2012.171. Epub 2012 Sep 12.

Abstract

Selective dopamine D(3) receptor (D(3)R) antagonists prevent reinstatement of drug-seeking behavior and decrease the rewarding effects of contextual cues associated with drug intake preclinically, suggesting that they may reduce drug craving in humans. GSK598809 is a selective D(3)R antagonist recently progressed in Phase I trials. The aim of this study was to establish a model, based on the determination of the occupancy of brain D(3)Rs (O(D(3))(R)) across species, to predict the ability of GSK598809 to reduce nicotine-seeking behavior in humans, here assessed as cigarette craving in smokers. Using ex vivo [(125)I](R)-trans-7-hydroxy-2-[N-propyl-N-(3'-iodo-2'-propenyl)amino] tetralin ([(125)I]7OH-PIPAT) autoradiography and [(11)C]PHNO positron emission tomography, we demonstrated a dose-dependent occupancy of the D(3)Rs by GSK598809 in rat, baboon, and human brains. We also showed a direct relationship between O(D(3))(R) and pharmacokinetic exposure, and potencies in line with the in vitro binding affinity. Likewise, GSK598809 dose dependently reduced the expression of nicotine-induced conditioned place preference (CPP) in rats, with an effect proportional to the exposure and O(D(3))(R) at every time point, and 100% effect at O(D(3))(R) values 72%. In humans, a single dose of GSK598809, giving submaximal levels (72-89%) of O(D(3))(R), transiently alleviated craving in smokers after overnight abstinence. These data suggest that either higher O(D(3))(R) is required for a full effect in humans or that nicotine-seeking behavior in CPP rats only partially translates into craving for cigarettes in short-term abstinent smokers. In addition, they provide the first clinical evidence of potential efficacy of a selective D(3)R antagonist for the treatment of substance-use disorders.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • CHO Cells
  • Cricetinae
  • Cricetulus
  • Dopamine Antagonists / pharmacology
  • Dopamine Antagonists / therapeutic use
  • Drug-Seeking Behavior / drug effects*
  • Drug-Seeking Behavior / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Models, Neurological
  • Papio anubis
  • Protein Binding / physiology
  • Rats
  • Receptors, Dopamine D3 / antagonists & inhibitors
  • Receptors, Dopamine D3 / metabolism*
  • Smoking / drug therapy*
  • Smoking / metabolism*
  • Smoking Cessation / methods
  • Translational Research, Biomedical / methods*

Substances

  • Dopamine Antagonists
  • Receptors, Dopamine D3