The mGlu5 receptor regulates extinction of cocaine-driven behaviours.
Drug Alcohol Depend 2014;
137:83-9. [PMID:
24576814 DOI:
10.1016/j.drugalcdep.2014.01.017]
[Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/07/2014] [Accepted: 01/13/2014] [Indexed: 11/24/2022]
Abstract
BACKGROUND
There is extensive evidence implicating the metabotropic glutamate 5 (mGlu5) receptor in aspects of addiction-related behaviours.
METHODS
Here, we used a well-characterized line of mGlu5-deficient mice to further examine the role of this receptor in cocaine-driven behaviours. We confirmed the previously reported deficit in hippocampal long-term potentiation and associated spatial learning impairment.
RESULTS
Despite a spatial learning deficit, mGlu5-deficient mice developed and maintained a conditioned place preference to cocaine, suggesting cocaine reward and Pavlovian conditioning are intact in these animals. Notably, however, mGlu5-deficient mice exhibited a marked deficit in the extinction of a cocaine-conditioned place preference compared to wild type littermates. Moreover, in a fixed ratio operant intravenous self-administration paradigm, both genotypes showed similar responding for cocaine over two different doses, while mGlu5-deficient mice displayed enhanced responding on a progressive ratio schedule. In addition, cue-induced drug-seeking after abstinence was exaggerated in mGlu5-deficient mice.
CONCLUSION
Collectively, these findings suggest that while the mGlu5 receptor may be involved in mediating the rewarding effects of cocaine, it appears necessary for the extinction of cocaine-driven behaviours.
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