Effects of chronic naltrexone treatment in rats on place preference and locomotor activation after acute administration of cocaethylene or ethanol plus cocaine.

When cocaine and ethanol are taken together a cocaine metabolite called cocaethylene is produced. Investigators have determined that cocaine, ethanol, and cocaethylene all produce a conditioned place preference when administered intraperitoneally. On the basis of the moderate success of naltrexone at attenuating the rewarding effects of ethanol and cocaine administered independently, we examined the ability of chronic naltrexone treatment (administered by means of subcutaneous implant across 6 days) to reduce the preference and motor-stimulating effects resulting from intraperitoneal administration of cocaethylene (Experiment 1) and the co-administration of ethanol with cocaine (Experiment 2) in outbred rats.