Ethanol consumption by C57BL/6 mice: influence of gender and procedural variables.

Both sexes of C57BL/6 (C57) mice consumed substantial quantities of ethanol without food or water deprivation whether access was continuous or limited. Food deprivation increased the amount of ethanol consumed, and the amount consumed depended upon when the animals were tested with reference to their daily food allotment. Ethanol consumption was greater if the mice were tested postprandially, high thirst motivation, rather than preprandially (approximately 10 vs. approximately 4.5 g/kg/30 min). Preference for ethanol over water, however, was greater when mice were under low thirst motivation (i.e., tested preprandially or with water available during the test). Compared to males, female mice consumed more of a high-ethanol concentration solution (10%) when access was continuous or limited to the first hour of the dark (active) phase of the circadian cycle. Also, in contrast to males, female mice exhibited increased ethanol consumption across days of drinking experience. Finally, although ethanol consumption under the food deprivation conditions of this experiment did not differ according to sex, females had higher blood ethanol concentrations than male C57 mice, a finding not previously reported for rodents but common to humans.