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Increased ethanol self-administration in delta-opioid receptor knockout mice
A J Roberts1, L H Gold, I Polis
1Department of Neuropharmacology, The Scripps Research Institute, La Jolla, California 92037, USA. aroberts@scripps.edu
Alcoholism, Clinical and Experimental Research
|October 5, 2001
Summary
Mice lacking the delta-opioid receptor (KO) showed increased ethanol preference and consumption. This suggests that reduced delta-receptor activity is linked to higher ethanol drinking behaviors, potentially influenced by anxiety levels.
Area of Science:
- Neuroscience
- Pharmacology
- Genetics
Background:
- The role of delta-opioid receptors in ethanol consumption remains unclear.
- Conflicting results exist regarding the effect of delta-receptor antagonism on ethanol drinking.
- Novel approaches are needed to understand opioid receptor involvement in ethanol intake.
Purpose of the Study:
- To investigate the role of delta-opioid receptors in ethanol drinking behavior.
- To examine ethanol preference and consumption in delta-opioid receptor knockout mice.
- To assess the impact of ethanol self-administration on anxiety-like behavior in these mice.
Main Methods:
- Ethanol drinking was assessed in delta-opioid receptor knockout (KO) mice using two-bottle-choice tests and an operant self-administration paradigm.
- Anxiety-like behaviors were measured in KO mice relative to wild-type (WT) controls.
- The study involved sequential testing: initial two-bottle-choice, operant self-administration, and a second two-bottle-choice test.
Main Results:
- Delta-opioid receptor KO mice initially did not prefer ethanol but developed a preference after operant self-administration.
- KO mice exhibited higher ethanol preference and self-administered more ethanol than WT mice.
- Ethanol consumption in KO mice was sufficient to reverse innate anxiety-like behaviors.
Conclusions:
- Reduced delta-opioid receptor activity is associated with increased ethanol preference and consumption.
- Delta-opioid receptors may modulate ethanol self-administration, potentially via effects on anxiety-related behaviors.
- These findings highlight a significant role for delta-opioid receptors in regulating ethanol intake.