Background: Quantitative models of choice, such as the matching law and behavioral economics, allow for the analysis of alcohol consumption within a choice context. Such models can provide further knowledge of phenotypic differences between selected lines of rats. The current study applied the generalized matching law to the ethanol (EtOH) and sucrose consumption of alcohol-preferring (P), nonpreferring (NP), and Sprague-Dawley (SD) rats.
Methods: Male P, NP, and SD rats were trained to consume increasing concentrations of EtOH and water in a limited access, 2-bottle choice procedure. The animals were then given concurrent access to pairs of differing EtOH solutions (2, 4, 6, and 10%, v/v) for 1 h/d. A subset of animals from each rat type was subsequently given access to 8% sucrose for 1 h/d for 5 days, and then concurrent access to pairs of differing sucrose solutions (3, 8, and 15%, w/v) for 1 h/d. The generalized matching law was used to assess the relationship between the relative EtOH and sucrose concentrations and the relative volumes of solutions consumed.
Results: The P rats consumed more EtOH and sucrose than the NP and SD rats overall. However, only the P rats consistently consumed disproportionately greater quantities of the higher EtOH concentration than the lower one, indicating overmatching. Additionally, all 3 types of rats displayed overmatching in the sucrose choice experiment.
Conclusions: These data provide further evidence of phenotypic differences between the P rats and other types of rats, and suggest that the generalized matching law can be a useful tool for describing rats' EtOH or sucrose consumption in a 2-bottle choice, limited access paradigm.