Behavioral evidence for different mechanisms of action for ethanol and anxiolytics.

1. Stimulus control was established in rats with 600 mg/kg ethanol and saline by employing a two-lever response choice task and an FR10 schedule of food reinforcement. 2. Once trained, rats were tested with lower doses of ethanol (300-525 mg/kg) and with chlordiazepoxide (1.25-5.0 mg/kg) or diazepam (0.32-1.25 mg/kg). The highest doses of each of these treatments were observed to produce ethanol-like responding and decreasing doses produced dose-related effects upon discriminative performance. 3. The ED50 for ethanol was 300 mg/kg, for chlordiazepoxide, 1.20 mg/kg and for diazepam, 0.55 mg/kg. 4. Graphic representation of the dose-response relationships suggested that these anxiolytics share a common site and/or mechanism of action that differs from that of ethanol.