The Opioid Peptides Enkephalin and β-Endorphin in Alcohol DependenceBiological Psychiatry Article in Press 27 June 2008
Experimental evidence indicates that the endogenous opioid system influences stress responses as well as reinforces effects of addictive drugs. Because stress is an important factor contributing to drug dependence and relapse, we have now studied ethanol preference in enkephalin– and β-endorphin–deficient mice under baseline conditions and after stress exposure.
Ethanol consumption was significantly reduced in the absence of β-endorphins, particularly in female knockout animals. Stress exposure results in an increased ethanol consumption in wild-type mice but did not influence ethanol-drinking in β-endorphin knockouts. Enkephalin-deficient mice showed no difference from wild-type mice in baseline ethanol preference but also showed no stress-induced elevation of ethanol consumption. Interestingly, we found a two-marker haplotype in the POMC gene that was associated with alcohol dependence in females in both cohorts.
Together these results indicate a contribution of β-endorphin to ethanol consumption and dependence.
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