The role of diet-induced taste changes and taste preference in ethanol intake of mice
Ethanol is perceived as having sweet and bitter components, and its acceptance and consumption levels have been linked to taste. While extensive research has been conducted to identify the genetic basis of alcoholism, studies have focused on mechanisms involved in the reward systems due to their outsized involvement in the broader field of substance use-related behaviors. However, given that taste acts as the primary behavioral gateway to alcohol consumption, it is imperative to understand its role in potentially shaping alcohol consumption to manage clinical tactics based on factors such as dietary intake and taste genetics. This Ph.D. project was designed to expand the current understanding of how dietary intake and taste preference influence the perception of ethanol. Using C57BL/6 mice as an animal model, we combined methods in 2-bottle preference testing, immunohistochemistry, and qRT-PCR to identify intersections between taste and ethanol consumption. In the first arm of the project, we investigated the effects of bitter or sweet diet-induced shifts in ethanol preference, and whether molecular and anatomical changes in taste-related functions were implicated in those behavioral shifts. While the molecular mechanism by which chronic bitter intake raises ethanol preference remains unclear, we demonstrated that a 4-week bitter diet increased the preference for ethanol, and that it had unexpected secondary effects on sweet perception and sweet- or umami-sensing T1R3-positive cells in taste buds. In the second arm of the project, inherent variation in the mRNA expression levels of taste genes were evaluated against ethanol preference patterns. Ethanol preference was found to be associated with bitter aversion in males, with no genetic association with sweet taste functions but correlations with T2R26 and T2R37 bitter receptor and GNAT3 taste transducing genes. Collectively, our findings add to the existing body of research on the role of taste in alcohol consumption by ruling out key bitter taste-related genes as molecular drivers of a bitter diet-driven shift in ethanol consumption, and also by demonstrating a genetic link between ethanol preference and bitter sensing or taste transducing capacities of male C57BL/6 mice. The implications of our findings highlight the need for continued research into the association between alcohol consumption and long-term effects of chronic bitter intake, as well as between alcohol consumption and variation in bitter gene expression.
Diet; Ethanol intake; Taste
Lin, Dave M.; Cleland, Thomas A.
Food Science and Technology
Ph. D., Food Science and Technology
Doctor of Philosophy
dissertation or thesis