The present experiments utilized an intermittent ethanol vapor exposure regimen to induce dependence. Ethanol vapor exposure can induce ethanol dependence (Rogers, Wiener, & Bloom, 1979) and intermittent vapor exposure (14 hours on, 10 hours off) induces a wide range of behaviors indicative of a dependent-like phenotype such as excessive ethanol self-administration in both fixed- and progressive-ratio schedules of reinforcement (Walker and Koob 2007; O'Dell et al. 2004) and increased anxiety- (Valdez et al. 2002) and depressive-like (Walker et al. 2010b) behaviors. The vapor exposure apparatus (La Jolla Alcohol Research, Inc., La Jolla, CA) allows for the animal's blood alcohol levels (BALs) to beikated according to desired target BALs. Target BALs over the course of the experiment were 175 – 225 mg% and were determined twice weekly by collecting the blood from the tail (~0.25 ml). Blood samples were centrifuged at 15000 rpm for 15 min and the 5 μl of plasma was assayed using the Analox AM1 (Analox Instruments Ltd., Lunenburg, MA). Single point calibrations of the Analox AM1 were conducted daily prior to each set of BAL determinations.
