Sex differences in alcohol drinking patterns during forced and voluntary consumption in rats

Wistar rats were studied during forced and voluntary alcohol consumption, and continuous or periodic access to ethanol (6%) v/v with different availability of fluids. Absolute volume of alcohol consumption was not different between sexes in any condition; however, females consumed significantly more alcohol than males on a g/kg basis in all conditions. These differences were significantly more extensive during continuous free-choice to alcohol and water than during forced alcohol consumption. Females showed greater alcohol preference than males only during continuous free-choice to alcohol and water. During periodic free-choice to alcohol and water condition, alcohol consumption was distributed during more hours throughout the day in females than males. During periodic free-choice to alcohol and to an isocaloric sweetened solution (ISS), intakes of ISS were very high compared to regular intakes of daily water; nevertheless, alcohol consumption was maintained to similar levels observed in continuous free-choice to alcohol and water and represented almost 50% of regular daily consumes of water in males and females. Free-choice for alcohol and ISS modified the usual pattern of alcohol consumption during the daily light-dark cycle in males and females and reduced the time devoted to drinking alcohol compared to other conditions, in which similar intakes were observed. Results show that the extent of the higher alcohol consumption in females than males and the changes in patterns of alcohol intake were dependent on the nature of the ingestion schedule.