Abstract
BACKGROUND: Most work to understand the controls of alcohol intake by animals involves the two-bottle choice method. Recent experiments involving other nutrients suggest that intakes are profoundly influenced by the number of nutrient choices available. Here, we extended these observations by measuring the alcohol consumption of mice and rats given multiple choices of water and alcohol. METHODS: Four experiments were conducted. In experiments 1 and 2, male C57BL6/J (B6) mice, 129X1/SvJ mice, or Sprague-Dawley rats received a series of six 72- or 48-hr tests in which the number of bottles of 10% alcohol and water was manipulated. One test involved the typical two-bottle choice. In the other five, the rodents always had six bottles with one, two, three, four, or five containing 10% alcohol and the rest containing water. In experiment 3, separate groups of B6 mice received for 16 days (a) the typical two-bottle test, (b) five alcohol bottles and one water bottle, (c) three alcohol bottles and three water bottles, or (d) one alcohol bottle and five water bottles. In experiment 4, groups of B6 mice received either a two-bottle test or five alcohol bottles and one water bottle for 24 days. RESULTS: In all experiments, the volume of alcohol consumed was strongly and positively related to the number of alcohol bottles available and inversely related to the number of water bottles available. The effect of alcohol availability on alcohol intake persisted for at least 24 days. CONCLUSIONS: Alcohol intake is strongly influenced by availability. The results point to a simple method of manipulating murine alcohol intake over a wide range. They provide an animal model that might be useful for understanding the influence of alcohol availability on human alcohol consumption.