A two-chamber contextual place preference apparatus was used for ethanol conditioned place preference (CPP) (Columbus Instruments, Columbus, OH). One chamber was white and had a striated floor texture and the other chamber was black with a hatched floor texture, separated by a removable divider. The whole apparatus was housed inside a sound-attenuating chamber (MedAssociates, St. Albans, VT). Sound and light levels were normalized. Animals were between the ages of 8 to 11 weeks old. Animals were habituated to the testing area for two hours between the hours of 0900 to 1200 prior to testing. The removable divider was closed during training and open during the habituation and testing sessions. On the day prior to the commencement of training, animals were allowed 30 minutes free access to both chambers. Neither +/+ nor Lwt/+ males showed a baseline preference for either chamber; therefore, equal numbers of mice received the ethanol unconditioned stimulus in either chamber. Animals were tested at the same time each day (1200) and given a single injection and immediately placed into one chamber for precisely five minutes. Saline and
