Limbic system mGluR5 availability in cocaine dependent subjects: a high-resolution PET [(11)C]ABP688 study

Neuroimage. 2014 Sep;98:195-202. doi: 10.1016/j.neuroimage.2014.04.061. Epub 2014 May 2.


Cocaine self-administration decreases type 5 metabotropic glutamate receptor (mGluR5) tissue concentrations in laboratory rats during early abstinence. These changes are thought to influence the drug's reinforcing properties and the ability of drug-related cues to induce relapse. Here, our goal was to measure brain regional mGluR5 availability in recently abstinent cocaine dependent humans. Participants meeting DSM-IV diagnostic criteria for current cocaine dependence (n=9) were recruited from the general population. mGluR5 availability (binding potential, non-displaceable; BPND) was measured with high-resolution positron emission tomography (PET HRRT) and [(11)C]ABP688. Compared to age- and sex-matched healthy controls (n=9), cocaine dependent subjects showed significantly lower BPND values in the ventral (bilateral: -28.2%, p=0.011), associative (right: -21.4%, p=0.043), and sensorimotor striatum (bilateral: -21.7%, p=0.045), amygdala (left: -26%, p=0.046) and insula (right: -23.3%, p=0.041). Among the cocaine users, receptor availabilities were related to abstinence (range: 2 to 14days). The longer the duration of abstinence, the lower the BPND values in the sensorimotor striatum (r=-0.71, p=0.034), left amygdala (r=-0.73, p=0.026) and right insula (r=-0.67, p=0.046). Compared to healthy controls, BPND values were significantly reduced in those who tested negative for cocaine on the PET test session in the ventral (p=0.018) and sensorimotor striatum (p=0.017), left amygdala (p=0.008), and right insula (p=0.029), but not in those who tested positive. Together, these results provide evidence of time-related mGluR5 alterations in striatal and limbic regions in humans during early cocaine abstinence.

Keywords: Abstinence; Addiction; Glutamate; Positron emission tomography; Relapse; Striatum.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Carbon Radioisotopes
  • Cocaine-Related Disorders / diagnostic imaging
  • Cocaine-Related Disorders / metabolism*
  • Female
  • Humans
  • Limbic System / diagnostic imaging
  • Limbic System / metabolism*
  • Male
  • Oximes
  • Positron-Emission Tomography
  • Pyridines
  • Receptor, Metabotropic Glutamate 5 / antagonists & inhibitors
  • Receptor, Metabotropic Glutamate 5 / metabolism*


  • 3-(6-methylpyridin-2-ylethynyl)cyclohex-2-enone-O-methyloxime
  • Carbon Radioisotopes
  • GRM5 protein, human
  • Oximes
  • Pyridines
  • Receptor, Metabotropic Glutamate 5