Genomic screen for QTLs underlying alcohol consumption in the P and NP ratlines

Selective breeding for voluntary alcohol consumption was utilized to establ ish the alcohol-preferring (P) and alcohol-nonpreferring (UP) rat lines. In breeding was initiated after 30 generations of selection and, after 19 gene rations of inbreeding, 384 F-2 intercross progeny were created to identify quantitative trait loci (QTLs) influencing alcohol consumption. We had repo rted previously a QTL on Chromosome (Chr) 4; additional markers genotyped o n Chr 4 have increased the maximum lod score from 8.6 to 9.2. This QTL acts in an additive fashion and continues to account for approximately 11% of t he phenotypic variability. The 95% confidence interval is 12.5 cM and inclu des the candidate gene, neuropeptide Y. Subsequent to the identification of the QTL on Chr 4, a genome scan was completed to identify additional QTLs influencing alcohol consumption. A lod score of 2.5 was obtained on Chr 3, syntenic to a region previously reported for alcohol preference in mice. An alysis of Chr 8 produced a lod score of 2.2 near the dopamine D2 and seroto nin Ib receptors, which have been previously reported as candidate genes fo r alcohol preference. Evidence for linkage to alcohol consumption was not f ound on any other chromosome. It therefore appears likely that, in addition to the QTL on Chr 4, multiple loci of small to moderate effect, such as th ose on Chrs 3 and 8, underlie the difference in alcohol consumption in the P/NP lines.