Oral ethanol reinforcement in the rat: effects of acute amphetamine

Six male Long Evans rats, reduced to 80% body weight by food restriction, were trained to lever press using 5% ethanol and water reinforcement on a concurrent FR8 FR8 schedule. After responding had stabilized, d-amphetamine (0.25 mg/kg, 0.50 mg/kg, and 1.00 mg/kg) or drug vehicle was injected 15 minutes before the 30-minute sessions. In comparison with the vehicle injections, the 0.25 mg/kg amphetamine dose was followed by a nonsignificant trend towards increased ethanol responding, the 0.50 mg/kg dose produced no trend, and the 1.00 mg/kg dose significantly decreased ethanol responding. These effects resemble those of amphetamine on food responding by food-deprived rats. Since both ethanol and amphetamine act upon brain catecholamine systems, possible involvement of catecholamines in reinforcement and arousal was discussed in relation to these results.