Dissociation between the aversive and pharmacokinetic effects of ethanol in female Fischer and Lewis rats

In humans and laboratory animal models, vulnerability to alcohol abuse is influenced by endogenous factors such as genotype. Using the inbred Fischer and Lewis rat strains, we previously reported stronger conditioned taste aversions (CTA) in male Fischer rats that could not be predicted by genotypic differences in alcohol absorption [Roma PG, Flint WW, Higley JD, Riley AL. Assessment of the aversive and rewarding effects of alcohol in Fischer and Lewis rats. Psychopharmacology (Berl) 2006;189:187-99]. The present study made similar assessments in Fischer and Lewis females via four-trial CTA induced by 1 or 1.5 g/kg intraperitoneal (IP) ethanol (n = 10-12/strain/dose) as well as measures of blood alcohol concentrations (BAC) at 15, 60 and 180 min post-injection with 1.5 g/kg IP ethanol or saline (n = 7-8/strain/dose). Dose-dependent CTAs were produced, but the strains did not differ from each other in these measures; however, BACs in the Lewis females were significantly higher than Fischer at all three time points. As with males of the Fischer and Lewis genotypes, a dissociation between BACs and the aversive effects of alcohol was observed. These data are the first assessments of these particular phenotypes in Fischer and Lewis females, and when considered with the historical data, suggest a Genotype × Sex interaction in the centrally mediated sensitivity to alcohol's aversive effects.