Blood alcohol concentrations after scheduled access in high-alcohol-preferring mice

Development of procedures yielding substantial blood alcohol concentrations during voluntary access to an alcohol solution in mice is necessary to further characterize genetic and neurobiologic mechanisms underlying alcohol self-administration. Although, in experimental situations, some populations of mice readily drink an alcohol solution, results from previous studies have not typically revealed high blood alcohol concentrations after voluntary access, probably because of the high alcohol metabolism rate in mice. Toward development of a murine drinking model, 36 selectively bred high-alcohol-preferring mice of both sexes were subjected to a 30-min scheduled-access procedure by using saccharin fading to gradually introduce an alcohol solution. Mice had ad libitum access to food and water 24 h a day. The alcohol solution was available 1 h after the start of the dark part of the cycle for 30 min per day, 5 days per week. After complete removal of saccharin from the drinking tubes, mice consistently drank 1.4 g/kg of a 10% [volume/volume (vol./vol.)] alcohol solution in 30 min. Analysis of tail blood samples, taken immediately after the end of the 30-min access period, indicated blood alcohol concentrations were tightly correlated with alcohol intakes (range, 6-130 mg/dl; average, nearly 60 mg/dl). A concentration-response function of 10%, 12%, 15%, 18%, and 21% (vol./vol.) alcohol solutions indicated an inverted U-shaped relation between alcohol intake and alcohol concentration, with peak intake of greater than 1.75 g/kg per 30 min when a 15% alcohol solution was available. No sex differences were seen. These findings indicate the utility of this procedure in obtaining pharmacologically relevant blood alcohol concentrations after voluntary oral self-administration of an alcohol solution in mice.