Conditioning procedures closely followed those used by Molina et al. (2006; 2007). Animals were food and fluid deprived 120 min before commencement of the conditioning session. This deprivation aimed at eliminating the confounding factor of differential stomach loading, that could affect absorption and distribution of ethanol. Next, they were individually placed in a square-shaped chamber lined with cotton. A 10 min habituation phase was conducted to familiarize subjects with the chambers. Immediately following habituation, animals in the paired group were weighed to the nearest 0.01 g (Sartorius, Gottingen, Germany) and intragastrically (i.g.) administered 0.5 or 2.0 g/kg ethanol. The rats were then returned to their individual holding chambers. Conditioning took place after animals were returned to the square-shaped chambers. In these chambers animals were given a conditioned stimulus (CS1) consisting of intraoral pulses of sucrose (10% v/v, 9 μl per pulse, pulse duration: 5 sec, interval between pulses: 55 sec). CS1 delivery took place either 5-20 or 30-45 min after ethanol (groups Early pairing and Late pairing, respectively) and was performed by connecting the intraoral cannula to the infusion pump.
