Repeated exposure to alcoholic beer does not induce long-lasting changes in alcohol self-administration and intake in sardinian alcohol-preferring and sardinian non-preferring rats

Aims: Rats avidly consume non-alcoholic beer, and addition of alcohol to non-alcoholic beer may function as a medium to induce intake of large amounts of alcohol in rats. The present study investigated whether Sardinian alcohol-preferring (sP) and Sardinian non-preferring (sNP) rats, initially exposed to non-alcoholic beer, and subsequently to non-alcoholic beer containing increasing concentrations of alcohol, would develop unusually high alcohol self-administration and drinking behaviours: (i) when alcohol was added to non-alcoholic beer, and (2) once beer was withdrawn and a plain alcohol solution was made available. Methods: In Experiment 1, rats were exposed to operant, 30-min/day self-administration sessions of non-alcoholic beer with increasing concentrations of alcohol [0, 2.5, 5, 7.5, and 10% (v/v)] for a total of 45days. After a brief beer-fading phase, the rats were exposed to self-administration sessions of a plain 10% (v/v) alcohol solution. In Experiment 2, the rats were exposed to non-alcoholic beer with increasing concentrations of alcohol [0, 2.5, 5, 7.5, and 10% (v/v)] and water under the 2-bottle choice regimen with unlimited access (24h/day) for a total of 35days. After a brief beer-fading phase, the rats were exposed to the choice between a plain 10% (v/v) alcohol solution and water. Results: sP and sNP rats did not differ in self-administration (Experiment 1) and intake (Experiment 2) of non-alcoholic beer. In Experiment 1, as alcohol content increased, the amount of self-administered alcohol increased progressively in sP rats (up to 11.2g/kg) and remained stable in sNP rats (approximately 0.65g/kg). When the plain 10% alcohol solution was available, the amount of self-administered alcohol in sP rats initially dropped, and tended to increaseup to approximately 0.6g/kgon continuing exposure. In sNP rats, their lever-pressing behaviour was rapidly extinguished after beer withdrawal. In Experiment 2, as alcohol content was increased, daily alcohol intake increased progressively in sP rats (up to 89g/kg) and averaged approximately 2.4g/kg in sNP rats. When the plain alcohol solution was available, daily alcohol intake in sP rats was initially low, reaching control values on continuing exposure; conversely, daily alcohol intake was completely suppressed in sNP rats. Conclusions: These results suggest that exposure to alcoholic beer resulted in unusually high intakes of alcohol in both sP and sNP rats for as long as non-alcoholic beer was added to alcohol; however, these high levels of alcohol self-administration and intake were not maintained once non-alcoholic beer was withdrawn.