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mu-Opioid receptor knockout mice do not self-administer alcohol
A J Roberts1, J S McDonald, C J Heyser
1Department of Neuropharmacology, The Scripps Research Institute, La Jolla, CA 92037, USA. aroberts@scripps.edu
Summary
Mu-opioid receptors are critical for ethanol reinforcement. Mice lacking these receptors did not self-administer ethanol and showed aversion, revealing a key neurobiological pathway for alcohol consumption.
Area of Science:
- Neuroscience
- Pharmacology
- Genetics
Background:
- Opioid peptides are long-suspected contributors to ethanol reinforcement.
- Opioid receptor antagonists reduce ethanol self-administration in rodents and prevent relapse in humans.
- The precise mechanism underlying these effects remains unclear.
Purpose of the Study:
- To investigate the specific role of the mu-opioid receptor in mediating ethanol self-administration.
- To utilize mu-opioid receptor knockout mice for direct examination of this receptor's function.
Main Methods:
- Studied ethanol self-administration using nosepoke and lever operant paradigms in mu-opioid receptor knockout mice.
- Assessed ethanol drinking behavior through multiple two-bottle choice tests.
- Employed genetically engineered mice lacking functional mu-opioid receptors.
Main Results:
- Mu-opioid receptor knockout mice exhibited no ethanol self-administration across all tested conditions.
- These mice demonstrated an aversion to ethanol under several experimental circumstances.
- Behavioral paradigms consistently showed a lack of ethanol intake in the absence of mu-opioid receptors.
Conclusions:
- Mu-opioid receptors play a critical role in mediating ethanol self-administration.
- These findings provide new insights into the neuropharmacological basis of ethanol reinforcement.
- The study highlights the importance of the mu-opioid system in alcohol consumption behaviors.