Dopamine mediates cocaine-induced conditioned taste aversions as demonstrated with cross-drug preexposure to GBR 12909.

Although cocaine readily induces taste aversions, little is known about the mechanisms underlying this effect. It has been suggested that its inhibitory effects at one of the monoamine transporters may be mediating this suppression. Using the cross-drug preexposure preparation, the present series of studies examined a possible role of dopamine (DA) in this effect. Male Sprague-Dawley rats were exposed to cocaine (18 mg/kg; Experiment 1) or the selective DA transporter (DAT) inhibitor GBR 12909 (50 mg/kg; Experiment 2) prior to the pairing of a novel saccharin solution with injections of GBR 12909 (32 mg/kg), cocaine (18 mg/kg) or vehicle in a conditioned taste aversion (CTA) procedure. Preexposure to cocaine attenuated aversions induced by itself but not aversions induced by GBR 12909 (Experiment 1). Conversely, preexposure to GBR 12909 attenuated aversions induced by itself and cocaine (Experiment 2). This asymmetry suggests that cocaine and GBR 12909 induce CTAs via similar, but non-identical, mechanisms. These data are discussed in the context of previous work demonstrating roles for dopamine, norepinephrine and serotonin in cocaine-induced CTAs.