RESUMPTION OF ETHANOL-SEEKING BEHAVIOR IN RATS

Reexposure to alcohol may induce subjective craving and relapse to dru g self-administration in ex-alcoholics. In this study we proposed a ra t model of ''first-drink''-induced drug-seeking relapse. Responding wa s established in Long Evens rats under a fixed-ratio [FRS:S-r] schedul e for oral ethanol. Substitution of water for ethanol solution resulte d in extinction of the self-administration. When responding for 8% eth anol and ethanol intake were stable for at least three consecutive 30 min sessions, ethanol delivery was discontinued and only three water d ipper cup presentations were available upon responding (3[FR5:water]). When the number of active lever presses decreased to a low stable lev el, responding was considered extinguished. In Experiment 1, subjects under ''extinction'' were challenged with three three 8% ethanol dippe r cup presentations. The re-exposure to ethanol was able to significan tly reinstate responding in all subjects. Latency to complete the etha nol presentation significantly decreased compared to the value observe d during the previous ''extinction'' session. In Experiment 2, other s ubjects were tested for extinction and then reexposed to 4, 8 or 16%;, ethanol. Ah three concentrations significantly increased active lever presses, but with different patterns of responding. The resumption of responding was linearly correlated to the ethanol concentration but n o significant dose-effect relationship was found. In Experiment 3, ree xposure to 8% ethanol in nondeprived rats induced a resumption of resp onding not significantly different from the effect observed in a restr icted diet condition. These results demonstrate that ethanol reexposur e is able to reinstate ethanol-seeking behaviour in rats with a past h istory of ethanol self-administration, and that this effect does not d epend on a food motivation drive related to the calorific value of eth anol.