Assunzione di bevande alcoliche palatabili nei ratti Sardinian alcohol-preferring e -non preferring: un modello sperimentale di induzione di dipendenza da alcol?

Background and Aims: Rats avidly consume nonalcoholic beer, and addition of alcohol to nonalcoholic 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 -non preferring (sNP) rats, initially exposed to nonalcoholic beer and subsequently to nonalcoholic beer containing increasing concentrations of alcohol, would develop unusually high alcohol self-administration and drinking behaviors once beer was removed and a plain alcohol solution was made available. Methods: In Experiment 1, rats were exposed to operant, 30-min/day self-administration sessions of nonalcoholic beer with increasing concentrations of alcohol [0%, 2.5%, 5%, 7.5%, and 10% (v/v)] for a total of 45 days. After a brief “beer-fading” phase, rats were exposed to self-administration sessions of a plain 10% (v/v) alcohol solution. In Experiment 2, rats were exposed to nonalcoholic 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 (24 hours/day) for a total of 35 days. After a brief “beer-fading” phase, 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 and intake of nonalcoholic beer. In Experiment 1, as alcohol content increased, the amount of self-administered alcohol increased progressively in sP rats (up to 1-1.2 g/kg) and remained stable in sNP rats (approximately 0.65 g/kg). When the plain 10% alcohol solution was available, the amount of self-administered alcohol in sP rats was initially markedly reduced, and tended to increase – up to approximately 0.6 g/kg – on continuing exposure. In sNP rats, lever-pressing behavior rapidly estinguished after beer removal. In Experiment 2, as alcohol content increased, daily alcohol intake increased progressively in sP rats (up to 8-9 g/kg) and averaged approximately 2.4 g/kg in sNP rats. When the plain alcohol solution was available, daily alcohol intake in sP rats was initially low and reached control values on continuing exposure. Conversely, daily alcohol intake was completely suppressed in sNP rats. Conclusions: These results suggest that prolonged exposures to a highly accepted and strongly reinforcing alcoholic beer failed to permanently alter alcohol self-administration and intake in sP and sNP rats.