The response to naltrexone in ethanol-drinking rats depends on early environmental experiences

► Individual variability in naltrexone response is a clinical problem. ► Environmental impact on drug response is examined in a rat model. ► Naltrexone reduces ethanol intake in rats reared in a risk environment. ► Naltrexone has no effect in rats subjected to beneficial rearing conditions. ► Environmental factors are important in identifying good responders to naltrexone.