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Mol Psychiatry. 2014 May;19(5):625-32. doi: 10.1038/mp.2013.51. Epub 2013 Apr 30.

Smoking but not cocaine use is associated with lower cerebral metabotropic glutamate receptor 5 density in humans.

Author information

1
Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland.
2
Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
3
1] Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Institute for Biomedical Engineering, University and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland.
4
Institute of Legal Medicine, University of Zurich, Zurich, Switzerland.
5
Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University of Zurich, Zurich, Switzerland.
6
1] Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University of Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
7
1] Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
8
1] Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
9
1] Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.

Abstract

Long-lasting neuroadaptations in the glutamatergic corticostriatal circuitry have been suggested to be responsible for the persisting nature of drug addiction. In particular, animal models have linked the metabotropic glutamate receptor 5 (mGluR5) to drug-seeking behavior and extinction learning. Accordingly, blocking mGluR5s attenuated self-administration of cocaine and other addictive drugs in rats. How these animal findings extend to humans remains unclear. Therefore, we investigated if human cocaine users (CU) exhibit altered mGluR5 availability compared with drug-naïve control subjects. Seventeen male controls (11 smokers) and 18 male cocaine users (13 smokers) underwent positron emission tomography with (11)C-ABP688 to quantify mGluR5 availability in 12 volumes of interest in addiction-related brain areas. Drug use was assessed by self-report and quantitative hair toxicology. CU and controls did not significantly differ in regional mGluR5 availability. In contrast, smokers (n=24) showed significantly lower mGluR5 density throughout the brain (mean 20%) compared with non-smokers (n=11). In terms of effect sizes, lower mGluR5 availability was most pronounced in the caudate nucleus (d=1.50, 21%), insula (d=1.47, 20%), and putamen (d=1.46, 18%). Duration of smoking abstinence was positively associated with mGluR5 density in all brain regions of interest, indicating that lower mGluR5 availability was particularly pronounced in individuals who had smoked very recently. Specifically tobacco smoking was associated with lower mGluR5 availability in both CU and controls, while cocaine use was not linked to detectable mGluR5 alterations. These findings have important implications regarding the development of novel pharmacotherapies aimed at facilitating smoking cessation.

PMID:
23628984
DOI:
10.1038/mp.2013.51
[Indexed for MEDLINE]
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