Pleiotropic effect of a locus on chromosome 4 influencing alcohol drinking and emotional reactivity in rats

A QTL search in a segregating F2 intercross between HEP (High-Ethanol Preferring line) and wistar-kyoto (WKY, a low-alcohol consuming strain) rats identified a locus on chromosome 4 linked to the consumption of a 5% alcohol solution offered as a free choice with water (Terenina-Rigaldie et al. submitted). In order to confirm and analyse the influence of this locus, F2 rats were selected according to their genotype at the markers flanking the QTL and bred in order to obtain two groups of rats homozygous HEP/HEP ('HIGH' line) or WKY/WKY ('LOW' line) at the QTL, the rest of the genome being randomly inherited from one or the other founder strain. These two groups of animals displayed large differences in emotional reactivity (open field, elevated-plus maze), sensitivity to taste reinforcers (saccharin, quinine) and alcohol consumption (either forced or as a free choice with water). These results confirm the influence of this locus on alcohol intake and emotional reactivity traits, and suggest a pleiotropic effect of the gene(s) involved. Current research aims at the identification of this (these) gene(s).