Thirty-one adult, male Wistar rats (Charles River), weighing 180-200 g at the start of the experiment, were housed two per cage in a temperature-controlled vivarium under a reversed light/dark cycle (lights off 06.00 h to 18.00 h). Animals were divided into six groups: (1) control (n = 9), received no training or alcohol exposure; (2) trained (n = 3), trained on the self-administration paradigm for 3 weeks (30 minute access to sweetened solution vs. water 5 days a week); (3) nondependent alcohol self-administering (n = 5), initially trained to self-administer alcohol vs. water for 3 weeks (30 minute access to alcohol, 5 days a week) and housed for 6 weeks similarly to the dependent groups described below but without exposure to alcohol vapors, during which they were tested for alcohol intake via alcohol self-administration twice a week (30 minute access); (4) alcohol dependent (n = 4), trained to self-administer alcohol vs. water for 3 weeks (30 minute access to alcohol, 5 days a week) and exposed to intermittent chronic alcohol vapors for the following 6 weeks to induce dependence during
