Cocaine preexposure fails to sensitize the acquisition of cocaine-induced taste aversions

In two separate experiments, rats were given either an intraperitoneal (IP) injection of 10 mg/kg cocaine once a day for 10 consecutive days (Experime nt 1) or a single IP injection of 40 mg/kg of cocaine (Experiment 2) prior to receiving repeated pairings of a novel saccharin solution with cocaine ( 32 mg/kg; subcutaneous; SC). Although vehicle-preexposed subjects given sac charin-cocaine pairings readily acquired an aversion to the cocaine-associa ted saccharin solution, subjects preexposed to cocaine (whether 10 times or only once) displayed a retarded acquisition of the aversion. That is, coca ine preexposure attenuated the acquisition of cocaine-induced taste aversio ns. There was no difference in the degree of attenuation between the two pr eexposure conditions. Thus, under conditions that are effective in inducing sensitization within other behavioral preparations there was no evidence-o f sensitized cocaine-induced taste aversions. The results from the present investigation are similar to reports from this laboratory and others demons trating that preexposure to cocaine, as with a range of other psychoactive drugs, results in weaker taste aversions. The basis for the attenuating eff ects of cocaine preexposure was discussed in terms of an adaptation to the aversive effects of cocaine. (C) 1999 Elsevier Science Inc.