Animal studies have provided some evidence for genetic factors influencing the role of the DYN/KOR system in motivational effects of ethanol. In some cases, clear species differences were noted (e.g., effects of KOR activation on home-cage ethanol drinking), but in most instances results in rats and mice were similar. Studies using inbred rodent strains and lines of rats/mice selectively bred for specific ethanol-related phenotypes have revealed differences in basal and ethanol-induced changes in DYN/KOR expression and function. Whether these differences contribute to related genetically-based behavioral differences in unclear. Given the rich information available on genetically-governed differences in ethanol drinking and related behaviors, expanded use of genetic models for studying DYN/KOR system involvement in these behaviors seems fruitful for future work. A limited number of studies have exploited use of animal models to examine how genetic-mediated deficiencies or overexpression of DYN/KOR may contribute to motivational effects of ethanol. Targeting such changes in specific brain regions will aid in elucidating mechanisms and circuitry underlying such effects.
