Taste cues control ethanol-induced conditioned taste avoidance but not conditioned tolerance

Abstract

This experiment tested the ability of taste cues to serve as the conditioned stimulus (CS) for conditioned tolerance to ethanol hypothermia. Rats were exposed to a differential Pavlovian conditioning procedure in which the manual oral infusion of one flavor solution was consistently followed by injection of ethanol (2.25 g/kg), whereas exposure to another flavor was followed by injection of saline (16 trials each). Control rats received saline after both flavors. Body temperature was recorded continuously using radio telemetry. Ethanol-treated rats developed tolerance to ethanol’s hypothermic effect and aversion for the ethanol-paired flavor. However, flavor had no effect on the expression of tolerance, indicating that taste was not an effective CS for conditioned tolerance. This outcome may represent an instance of selective association in which taste cues more readily gain control over ethanol’s effect on ingestive behavior, whereas environmental cues more readily gain control over ethanol’s thermal effect. These results may also bear on the hypothesized role that ethanol’s thermal effect plays in ethanol self-administration and ethanol-induced conditioned taste aversion.