Vapour exposure was used because it allows a high degree of control over brain alcohol exposure at pharmacologically active levels, and induces behavioural and molecular changes relevant for the pathophysiology of alcoholism (Heilig & Koob, 2007). A total of 53 exposed animals and 24 matched controls were used. Exposure was done as described previously (Rimondini et al. 2002). Briefly, stainless-steel and glass chambers were used, and alcohol was pumped into heated stainless-steel coils connected to the airflow. Final alcohol concentration was adjusted by changing the pump flow, and was monitored via a spectrometer. Exposure was for 17 h during each 24-h period (on 16:00 hours, off 09:00 hours). Rats were allowed to habituate to the chambers for 1 wk, then exposed to a low alcohol concentration for 1 wk, and finally exposed to alcohol vapour to induce dependence for 7 wk. Control animals were kept with normal airflow. Each week all rats were weighed, and random subjects (n=6–8) were tested for blood alcohol concentration. Blood was collected from the lateral tail vein, and serum assayed for alcohol using an NAD/NADPH-spectrophotometric assay kit (Sigma Aldrich Inc., USA) according to the manufacturer’s instructions.
