Self-administration of ethanol: towards the location of predisposing polygenes in quasi-congenic animal models.

Alcohol consumption by C57BL/6By background and BALB/cJ donor strains, and by two recently developed quasi-congenic QTL-introgression strains, which share about 96% of their genes with the background strain, was studied in a limited access paradigm. Alcohol and water were offered for 60 min per day using modified pipettes on a drinking cage. Increasing concentration of alcohol solutions, 3, 6, and 12%, were given for days 1-7, 8-14, and 15-22, respectively. Consumption of the 12% alcohol solution was highest in C57BL/6By (0.72 g/kg/h), lowest in BALB/cJ (0.14 g/kg/h). The B6.Cb4i5 beta 13 quasi-congenic strain, in spite of its genetic similarity to the C57BL/6By background strain, consumed significantly less alcohol (0.41 g/kg/h) than the background strain. The results suggest that polygenes that reduce alcohol consumption were introgressed from the BALB/cJ donor strain into the C57BL/6By background strain, and that the b4i5 series of the B6.C quasi-congenic QTL-introgression strains may be useful in mapping genes that influence alcohol-related behaviors. Locations of the introgressed candidate polygenes were tentatively identified by analyzing microsatellite maps of two of the quasi-congenic strains.