Acetaldehyde and morphine interaction in the preexposure conditioned taste aversion paradigm in the rat

The interaction between acetaldehyde, the primary metabolite of ethanol, and morphine was examined in the preexposure conditioned taste aversion (CTA) paradigm. Rats that were preexposed to acetaldehyde did not display a CTA to morphine. While acetaldehyde at the dose tested did not induce a strong CTA, morphine preexposure, however, reversed the decrease in saccharin associated with acetaldehyde injection thus reflecting a symmetrical interaction between acetaldehyde and morphine. Implications for a mechanism of ethanol-opiates interaction are discussed.