Reinstatement of ethanol seeking in rats: Behavioral analysis

The reinstatement model has been repeatedly used to study relapse to heroin - or cocaine-seeking behaviour in rats. The aim of the present study was to evaluate basic behavioral parameters of cue-induced reinstatement of ethan ol seeking in a within-session paradigm. Rats were trained to respond for e thanol in an oral self-administration procedure where each lever press resu lted in presentation of 0.3 ml of 8% ethanol from a liquid dipper. In the r einstatement paradigm operant behaviour was first extinguished for 20 or 60 min by switching the dipper off. Then, ethanol-associated stimuli were non contingently delivered and reinstatement of responding was assessed. Delive ries of the empty dipper, i.e., visual/auditory cues only, did not result i n any reinstatement. In contrast, 15 random presentations of the dipper con taining either ethanol (4-8%; v/v) or water significantly reinstated ethano l seeking. In a control self-administration experiment responding dropped t o nonsignificant levels when water was substituted for ethanol. The magnitu de of reinstatement did not depend on the duration of the extinction phase. These results seem to indicate that in the present paradigm reinstatement of ethanol seeking is driven by a compound stimulus including the visual/au ditory cues and some nonspecific sensory properties of liquid available in the dipper. (C) 2000 Elsevier Science Inc.