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Behav Brain Res. 2018 Nov 27;359:498-501. doi: 10.1016/j.bbr.2018.11.039. [Epub ahead of print]

Antagonism of μ-opioid receptors reduces sensation seeking-like behavior in mice.

Author information

1
Department of Molecular Neuropharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland.
2
Department of Molecular Neuropharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland. Electronic address: nfprzewl@cyf-kr.edu.pl.

Abstract

Novelty- and sensation-seeking behaviors induce activity of the brain reward system and are associated with increased susceptibility to drug abuse. Endogenous opioids have been implicated in reward-related behavior; however, the involvement of specific opioid receptors in the mechanism of sensation seeking is unknown. Here, we show that selective inhibition of opioid receptors reduce operant sensation seeking in mice. Administration of naltrexone (a nonselective opioid antagonist) reduced instrumental responding for sensory stimuli at one of the tested doses (2 mg/kg). More robust effects were observed in the case of cyprodime, a selective μ opioid receptor antagonist, which reduced instrumental responses by ∼50% at doses of 0.5 mg/kg and larger. Conversely, selective δ and κ receptor antagonists (naltrindole and nor-binaltorphimine, respectively) had no effect on sensation-seeking behavior. Importantly, while naltrexone produces aversion in the conditioned place preference test, cyprodime had no such effect. Therefore, reduced instrumental responding was not correlated with aversive effects of the opioid antagonists. In conclusion, our results revealed a novel mechanism of action of selective opioid receptors antagonists, which may have relevance for their efficacy in the treatment of drug abuse.

KEYWORDS:

Conditioned place aversion; Opioids; Sensation seeking; μ-Opioid receptor

PMID:
30500427
DOI:
10.1016/j.bbr.2018.11.039

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