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Neuropharmacology. 2016 Sep;108:14-23. doi: 10.1016/j.neuropharm.2016.04.010. Epub 2016 Apr 14.

Mu-opioid receptor activation in the medial shell of nucleus accumbens promotes alcohol consumption, self-administration and cue-induced reinstatement.

Author information

1
Department of Neurology, The Wheeler Center for the Neurobiology of Addiction, Alcoholism and Addiction Research Group, University of California, San Francisco, CA, USA. Electronic address: jocelyn.richard@jhu.edu.
2
Department of Neurology, The Wheeler Center for the Neurobiology of Addiction, Alcoholism and Addiction Research Group, University of California, San Francisco, CA, USA. Electronic address: howard.fields@ucsf.edu.

Abstract

Endogenous opioid signaling in ventral cortico-striatal-pallidal circuitry is implicated in elevated alcohol consumption and relapse to alcohol seeking. Mu-opioid receptor activation in the medial shell of the nucleus accumbens (NAc), a region implicated in multiple aspects of reward processing, elevates alcohol consumption while NAc opioid antagonists reduce it. However, the precise nature of the increases in alcohol consumption, and the effects of mu-opioid agonists on alcohol seeking and relapse are not clear. Here, we tested the effects of the mu-opioid agonist [D-Ala(2), N-MePhe(4), Gly-ol]-enkephalin (DAMGO) in rat NAc shell on lick microstructure in a free-drinking test, alcohol seeking during operant self-administration, extinction learning and expression, and cue-reinforced reinstatement of alcohol seeking. DAMGO enhanced the number, but not the size of drinking bouts. DAMGO also enhanced operant alcohol self-administration and cue-induced reinstatement, but did not affect extinction learning or elicit reinstatement in the absence of cues. Our results suggest that mu-opioid agonism in NAc shell elevates alcohol consumption, seeking and conditioned reinforcement primarily by enhancing the incentive motivational properties of alcohol and alcohol-paired cues, rather than by modulating palatability, satiety, or reinforcement.

KEYWORDS:

Alcohol; Extinction; Mu-opioid receptor; Nucleus accumbens; Reinstatement; Self-administration

PMID:
27089981
PMCID:
PMC4912898
DOI:
10.1016/j.neuropharm.2016.04.010
[Indexed for MEDLINE]
Free PMC Article

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