A recent review has discussed several important features of gene–environment interaction research (Sher et al. 2010). For example, the social environment plays such a crucial role in shaping drinking behaviors in humans, but it is difficult to identify corresponding rat and mouse behaviors and environmental factors. One example of a study analyzing gene– environment interactions in animals (Hansson et al. 2006) compares the influence of environmental stress in a rat line selectively bred for high alcohol preference (i.e., the Marchigian-Sardinian preferring rats) with their nonselected control group. The investigators found that the genetically “enriched” rats were more sensitive than the control animals to the effects of environmental stress on reinstatement of previously extinguished alcohol drinking (i.e., the alcohol-preferring rats resumed alcohol drinking more easily after being exposed to a stressor). Moreover, the differences resulted, at least in part, from variations between high-drinking and low-drinking animals in a gene encoding a receptor for corticotropin-releasing hormone (CRH) (which is involved in the body’s stress response) and in the expression of that gene (Hansson et al. 2006). Thus, this study demonstrated an interaction between a specific genotype and an environmental factor (i.e., stress).
