Do taste factors contribute to the mediation of ethanol intake? Ethanol and saccharin-quinine intake in three rat strains

Abstract

Several recent studies have suggested that ethanol-preferring rodents may also have an affinity for sweet solutions (saccharin, sucrose) and, conversely, that saccharin preference may predict ethanol preference. The purpose of the present investigation was to determine whether intake of ethanol and saccharin-quinine (SQ) solutions would be related in three nonselected strains of rats who differ in their ethanol preference: Lewis, Wistar Kyoto, and Wistar. In the first phase of the experiment, all animals were presented with an ascending series of ethanol solutions (2 to 10%) in free choice with water, followed by a 10-day maintenance period of 10% ethanol with water. In the second phase, the same animals were presented with an ascending series of SQ solutions (saccharin: 0.4%, quinine: 0.001 to 0.04%) in free choice with water, followed by a 10-day maintenance period of 0.4% saccharin with 0.04% quinine and water. The results revealed an absence of a direct relationship between ethanol and SQ consumption. The ethanol-nonpreferring Lewis rats showed a greater preference for the SQ solutions than Wistar Kyoto rats, whereas the ethanol-preferring Wistar Kyoto strain consistently consumed significantly less SQ. Wistar rats showed relatively stable consumption levels for both solutions that fell between those of the other two strains. These results suggested that the relationship between ethanol and SQ preference in rats was not a direct one and did not support the findings in the literature of a simple overall positive relationship between sweet and ethanol preference. These data do, however, provide further evidence for taste factors in the mediation of self-selection of ethanol in rats.