given access to 15% ethanol and water, and in Experiment 2 we used a single-bottle (of 20% ethanol) no-choice procedure standardized as a model of excessive alcohol consumption by Rhodes et al. (2005; 2007). In a standard single-bottle DID procedure, 20% ethanol is the concentration of choice as it elicits high alcohol intakes being the only fluid available during the access period but in the modified two-bottle choice DID procedure assessing ethanol preference, a slightly lesser ethanol concentration, 15%, is used as mice in this procedure (Blednov and Harris, 2008; Dhaher et al., 2009) have a choice between water and ethanol and the 20% ethanol solution is not preferred. In both DID procedures, the mice were given access to ethanol for 2 h for days 4 to 6 and then on day 7 (test day), access was increased to 4 h. As has been reported by Rhodes et al. (2005; 2007) and Sparta et al. (2008), using this ‘escalation’ procedure allows for excessive alcohol intakes on day 7 which may then be more responsive to pharmacological manipulations. In Experiment 3 (the injection experiment), mice were housed 5 to a cage and each cage was treated as a separate group. In
