Ethanol flavor preference conditioned by intragastric carbohydrate in rats

The unpalatable flavor of ethanol solutions greater than approximately 6% may limit their consumption by rats. We determined if ethanol flavor avoidance, like bitter or sour taste avoidance, can be reversed by intragastric (IG) carbohydrate conditioning. Ad lib fed rats drank 5% ethanol and a matched flavor (0.05% citric acid+0.5% maltodextrin, CM) on alternate days. For control rats, postingestive effects were equated: when they drank one solution they were infused IG with the other. Conditioned rats were also infused with 5% ethanol when they drank CM, but when they drank 5% ethanol they were infused with CM + 16% maltodextrin, a potent reward in flavor preference learning. In choice tests, only the conditioned rats preferred ethanol to CM; both groups preferred 5% ethanol to water. Conditioned rats but not controls preferred ethanol to water when the concentration was raised to 10%, and sustained their preference when the infusate carbohydrate was gradually removed. When ethanol concentration was gradually raised to 25%, ethanol preference declined from 48% to 30% in the control rats and from 84% to 50% in the conditioned rats. Thus, ethanol flavor avoidance can be reversed or reduced by postingestive nutritive conditioning, which may combine with the pharmacological effects of ethanol to produce the acquired appetite for the flavor of alcoholic beverages.