Following the one-month dependence induction period, all animals were tested for operant ethanol self-administration twice weekly 6 hours into withdrawal (i.e. acute withdrawal). It has been previously shown that following 6 hrs of withdrawal, the BALs of ethanol-experienced animals that had achieved a BAL of approximately 225 mg% following ethanol vapor exposure have returned to baseline levels (Gilpin et al., 2009). BALs were collected immediately before the ethanol vapor terminated on test days to confirm that the animal's BALs were within the target range. Following each test, the rats were returned to ethanol vapor apparatus and were re-exposed to ethanol vapor between tests. Thus, each post-dependence self-administration session was conducted under identical conditions of acute withdrawal in dependent animals.
