The discriminative stimulus properties of ethanol and acute ethanol withdrawal states in rats.

Twelve male Sprague-Dawley rats were trained in a standard two-choice Drug 1-Drug 2 discrimination task utilizing 3.0 mg/kg chlordiazepoxide (CDP, an anxiolytic drug) and 20 mg/kg pentylenetetrazol (PTZ, an anxiogenic drug) as discriminative stimuli under a VR 5-15 schedule of food reinforcement. Saline tests conducted at specific time points after acute high doses of ethanol (3.0 and 4.0 g/kg) indicated a delayed rebound effect, evidenced by a shift to PTZ-appropriate responding. Insofar as such a shift in lever selection indexes a delayed anxiety-like state, this acute 'withdrawal' reaction can be said to induce an affective state similar to that seen with chronic ethanol withdrawal states. Ethanol generalization tests: (1) resulted in a dose- and time-dependent biphasic generalization to CDP, (2) failed to block the PTZ stimulus and (3) failed to block the time- and dose-dependent elicitation of an ethanol-rebound effect. These data suggest that ethanol's anxiolytic effects are tenuous.