γ-Hydroxybutyric acid (GHB) suppresses alcoholʹs motivational properties in alcohol-preferring rats

γ-Hydroxybutyric acid (GHB) reduces alcohol drinking, promotes abstinence from alcohol, suppresses craving for alcohol, and ameliorates alcohol withdrawal syndrome in alcoholics. At preclinical level, GHB suppresses alcohol withdrawal signs and alcohol intake in rats. The present study was designed to investigate whether GHB administration was capable of affecting alcoholʹs motivational properties (the possible animal correlate of human craving for alcohol) in selectively bred Sardinian alcohol-preferring rats. To this aim, rats were initially trained to lever press for alcohol (15%, vol/vol) under a procedure of operant, oral alcohol self-administration (fixed ratio 4 in 30-min daily sessions). Once responding for alcohol had stabilized, rats were divided into two groups and allocated to two independent experiments. Experiment 1 assessed the effect of GHB (0, 25, 50, and 100 mg/kg, i.p.) on breakpoint for alcohol, defined as the lowest response requirement not achieved by each rat when exposed to a single-session progressive ratio schedule of reinforcement. Experiment 2 assessed the effect of GHB (0, 25, 50, and 100 mg/kg, i.p.) on single-session extinction responding for alcohol (alcohol was absent and unreinforced responding was recorded). Breakpoint and extinction responding for alcohol are reliable indexes of alcoholʹs motivational strength. In Experiment 1, all doses of GHB reduced—by approximately 20% in comparison to saline-treated rats—breakpoint for alcohol. In Experiment 2, administration of 25, 50, and 100 mg/kg GHB reduced—by approximately 25%, 40%, and 50%, respectively, in comparison to saline-treated rats—extinction responding for alcohol. Conversely, no dose of GHB altered breakpoint and extinction responding for sucrose (3%, wt/vol) in two independent subsets of Sardinian alcohol-preferring rats. Together, these data suggest that GHB administration specifically suppressed alcoholʹs motivational properties in Sardinian alcohol-preferring rats. These results are consistent with the anticraving properties of GHB observed in clinical studies.