Fig. 1.

Overview of the experimental protocol. The experiment was divided into four parts: a animals consumed ethanol in their home cage using the ethanol escalation model; b phase 1: following the establishment of baseline ethanol consumption using the DID method animals were divided into two groups with group A receiving GSK1521498 and group B receiving naltrexone as the test compound; c phase 2: following a 2-week wash-out period, DID was re-established and a cross-over design was employed such that group A received naltrexone and group B received GSK1521498 as the test compound; d compound specificity was tested using a 2 % sucrose DID protocol