Alcohol-preferring P rats exhibit aversion-resistant drinking of alcohol adulterated with quinine

Understanding why some people continue to drink alcohol despite negative consequences and others do not is a central problem in the study of alcohol use disorder (AUD). In this study, we used alcohol-preferring P rats (a strain bred to prefer to drink alcohol, a model for genetic risk for AUD) and Wistar rats (control) to examine drinking despite negative consequences in the form of an aversive bitter taste stimulus produced by quinine. Animals were trained to consume 10% ethanol in a simple Pavlovian conditioning task that paired alcohol access with an auditory stimulus. When the alcohol was adulterated with quinine (0.1 g/L), P rats continued to consume alcohol + quinine at the same rate as unadulterated alcohol, despite a demonstrated aversion to quinine-adulterated alcohol when given a choice between adulterated and unadulterated alcohol in the home cage. Conversely, Wistar rats decreased consumption of quinine-adulterated alcohol in the task, but continued to try the alcohol + quinine solution at similar rates to unadulterated alcohol. These results indicate that following about 8 weeks of alcohol consumption, P rats exhibit aversion-resistant drinking. This model could be used in future work to explore how the biological basis of alcohol consumption and genetic risk for excessive drinking lead to drinking that is resistant to devaluation.