Influences of Β-Endorphins in Ethanol Consumption Patterns and Aquisition of a Conditioned Taste Aversion Mediated by the Drug.

ABATE P; CAEIRO X; VIVAS LM; MOLINA JC

Revista Argentina de Ciencias del Comportamiento

UNC FAC DE PSICOLOGIA

Lugar: CORDOBA; Año: 2009 vol. 1 p. 25 - 35

1852-4206

Rewarding effects of ethanol may be mediated in part byendogenous opioids. Ethanol alters β-endorphin synthesis and release. β-endorphin heterozygous (HT) and knockout (KO) mice consume higherlevels of a low-concentrated alcohol solution and show heightenedpredisposition to self-administer ethanol in comparison with wild-type(WT) mice (Grisel et al., 1999). This study was conducted in order to: i) reanalyzeand extend previous results in terms of ethanol consumptionprofiles of β-endorphin deficient mice; and ii) analyze conditioned aversivelearning mediated by ethanol postabsorptive effects as a function of geneticcapabilities to synthesize β-endorphin. In Experiment 1, mice wereevaluated in terms of consumption of a low (7%) ethanol solution in a twobottlefree choice paradigm. Ethanol concentration was then increased to 10% and voluntary intake consumption was tested. WT mice displayedsignificantly higher consumption levels and ethanol-preference scores thandid KO mice, independently from ethanol concentration. HT mice drankmore ethanol than did KO mice. In Experiment 2, mice (KO, HT and WT)were tested in a conditioned taste aversion paradigm in which a sodiumchloride (NaCl) solution was paired with a 2-g/kg ethanol dose. Only HTand KO displayed a conditioned aversion when using 2-g/kg ethanol asunconditioned stimulus. The present results indicate that total or partialdeficiency of β-endorphin synthesis reduces ethanol preference andconsumption. Furthermore, this study indicates that the lack of β-endorphinsynthesis exacerbates ethanol’s aversive postabsorptive effects which can inturn modulate self-administration patterns of the drug.