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

Area of Science:

• Neuroscience
• Addiction Research
• Molecular Imaging

Background:

• Cocaine self-administration in rats reduces type 5 metabotropic glutamate receptor (mGluR5) concentrations during early abstinence.
• These mGluR5 changes may affect cocaine's reinforcing properties and cue-induced relapse.
• Understanding mGluR5 availability in abstinent humans is crucial for addiction treatment.

Purpose of the Study:

• To measure brain regional mGluR5 availability in recently abstinent cocaine-dependent individuals.
• To investigate the relationship between mGluR5 availability, abstinence duration, and cocaine use status.

Main Methods:

• Used high-resolution positron emission tomography (PET HRRT) with [(11)C]ABP688 to measure mGluR5 binding potential (BPND).
• Recruited 9 participants meeting DSM-IV criteria for cocaine dependence and 9 age/sex-matched healthy controls.
• Compared mGluR5 BPND between cocaine-dependent subjects and controls, and analyzed correlations with abstinence duration and urine test results.

Main Results:

• Cocaine-dependent subjects showed significantly lower mGluR5 BPND in the ventral striatum, associative striatum, sensorimotor striatum, amygdala, and insula compared to controls.
• Among cocaine users, longer abstinence duration correlated with lower mGluR5 BPND in the sensorimotor striatum, left amygdala, and right insula.
• Reduced mGluR5 BPND was observed in cocaine users who tested negative for cocaine, but not in those who tested positive.

Conclusions:

• Provides evidence for time-related alterations in mGluR5 availability in human striatal and limbic regions during early cocaine abstinence.
• Suggests that mGluR5 availability may serve as a biomarker for early cocaine abstinence.
• Findings highlight the role of the mGluR5 system in the neurobiology of cocaine addiction and recovery.