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Brain regional mu-opioid receptor function in rat lines selected for differences in alcohol preference
Sanna L Soini1, Petri Hyytiä, Esa R Korpi
1Department of Pharmacology and Clinical Pharmacology, University of Turku, Itäinen Pitkäkatu 4B, FIN-20520 Turku, Finland. sanna.soini@utu.fi
European Journal of Pharmacology
|July 30, 2002
Summary
Brain mu-opioid receptor function differs between alcohol-preferring and avoiding rats. These differences in mu-opioid receptor (MOR) system activity may underlie innate alcohol preference behaviors.
Area of Science:
- Neuroscience
- Pharmacology
- Genetics
Background:
- Opioid peptides are implicated in alcohol's reinforcing effects.
- Understanding the mu-opioid receptor (MOR) system's role is crucial for alcohol preference research.
Purpose of the Study:
- To investigate MOR system function in rat lines selectively bred for alcohol preference (AA) and avoidance (ANA).
- To determine if MOR functional coupling to G proteins correlates with innate alcohol preference.
Main Methods:
- Autoradiographic assessment of G protein coupling via [35S]GTPgammaS binding stimulated by Tyr-D-Ala-Gly-N(Me)Phe-Gly-ol-enkephalin.
- Examined binding in brain sections of AA and ANA rats.
- Correlated morphine-induced locomotor activity with G-protein activation in specific brain regions within the AA line.
Main Results:
- Significantly increased MOR-G protein coupling in the striatal patches and substantia nigra reticulata of AA rats compared to ANA rats.
- Positive correlation found between morphine-induced activity and G-protein activation in the substantia nigra compacta and nucleus accumbens core within the AA line.
Conclusions:
- Brain region-specific differences in mu-opioid receptor function are evident between rats with differing innate alcohol preferences.
- MOR system variations may contribute to the genetic basis of alcohol preference.