Behaviourally specific interactions between naloxone and beta-phenylethylamine in an operant drug discrimination procedure in rats

Rats were trained to discriminate phenylethylamine (PEA) at 30 mg/kg (IP). In subsequent generalization tests, it was found that naloxone had no effect on the discriminative stimulus (cue) properties of PEA, but it did potentiate PEA's dose-related rate suppressant effects. Thus the potentiation by naloxone of PEA's effects was behaviourally specific and confined to drug effects on motoric behaviours. These data support the results of previous in vivo and in vitro studies, which suggest that interactions between endogenous PEA and endorphin systems may be functionally important. Such interactions could be of significance in stress-related behavioural disorders.