Ethanol self-administration in ALKO rats: I. Effects of selection and concentration

The ALKO Alcohol Accepting (AA) rats and Alcohol Non-Accepting (ANA) rats were used to study the relationship between ethanol preference in a two-bottle choice paradigm and oral ethanol self-administration in an operant conditioning paradigm. Ethanol served as a positive reinforcer in the preferring AA line. Under a continuous reinforcement schedule (FR 1), ethanol deliveries were consistently greater than water (vehicle) deliveries and varied as an orderly inverted U-shaped function of ethanol concentration. Conversely, in nonpreferring ANA animals, ethanol did not serve as a reinforcer. Findings obtained with the AA rats were compared with those obtained with Sprague-Dawley rats. Sprague-Dawley rats maintained higher levels of responding and greater ethanol intake, relative to AA rats, at all concentrations of ethanol tested. The data are consistent with evidence that genotype is a critical factor in determining the extent to which ethanol serves as a reinforcer. The results also suggest that ethanol preference and the maintenance of ethanol reinforced behavior under operant conditions appear to have some common mechanisms. However, since the selection for ethanol preference in AA rats apparently did not maximize the maintenance of ethanol-reinforced behavior in an operant paradigm, ethanol drinking behavior in the preference paradigm may not be completely generalizable to that observed in the operant model.