Bitter taste function-related genes are implicated in the behavioral association between taste preference and ethanol preference in male mice

Abstract

Alcohol use disorder in humans is highly heritable, and as a term is synonymous with alcoholism, alcohol dependence, and alcohol addiction. Defined by the NIAAA as a medical condition characterized by an impaired ability to stop or control alcohol use despite adverse social, occupational, or health consequences, the genetic basis of alcohol dependence is much studied. However, an intriguing component to alcohol acceptance exists outside of genetics or social factors. In fact, mice of identical genetic backgrounds without any prior experience of tasting ethanol display widely varying preferences to it, far beyond those seen for typical taste solutions. Here, we hypothesized that a preference for ethanol, which tastes both bitter and sweet to humans, would be influenced by taste function. Using a mouse model of taste behavior, we tested preferences for bitter and sweet in mice that, without training or previous experience, either preferred or avoided ethanol solutions in consumption trials. Data showed clear sex differences, in which male mice that preferred ethanol also preferred a bitter quinine solution, whereas female mice that preferred ethanol also preferred a sweet sucralose solution. Male mice preferring ethanol also exhibited lower expression levels of mRNA for genes encoding the bitter taste receptors T2R26 and T2R37, and the bitter transducing G-protein subunit GNAT3, suggesting that the higher ethanol preference observed in the male mice may be due to bitter signaling, including that arising from ethanol, being weaker in this group. Results further support links between ethanol consumption and taste response, and may be relevant to substance abuse issues in human populations.