This was similar to the one-bottle DID test described previously (Rhodes et al., 2005) except that 2 bottles, one containing 15% ethanol and the other water, were used (Blednov and Harris, 2008). Once stable ethanol consumptions were reached, we measured ethanol intake after 2 days of saline (day 2 in graphs) and grouped mice to provide similar levels of ethanol intake and preference. The ethanol and water bottles remained in place for 3 hours. After their removal, mice had unlimited access to 1 bottle of water. Bottle positions during 3-hour access were changed daily to avoid potential position preferences. Drinking began 3 hours after lights off. Measurements of ethanol intake, preference, and total fluid intake were averaged over 2 days with different bottle positions. Each point in the graphs (days 2, 4, 6, etc.) represents the average of 2-day periods of measurement. For example, day 2 is the average of days 1–2 after saline, and day 4 is the average of days 3–4 after either saline or drug. Separate groups of mice were used for the two different drinking tests.
