Evidence from behavioural and in vitro receptor binding studies that the enkephalinergic system does not mediate...

The behavioural disturbances produced by acute exposure to ethanol have been related to changes in function of the opioid systems in the CNS. However, evidence in the literature is conflicting. The present report concerns the possible role of the enkephalinergic system in the mediation of acute ethanol effects. We used rats to study the ability of a selective opioid delta receptor antagonist (ICI 154129) to prevent the effect of ethanol on pain sensitivity, body temperature, sensorimotor performance and level of consciousness. Furthermore, in vitro receptor binding was measured to investigate whether or not ethanol, within a non-lethal concentration range, would change the binding parameters of the delta receptor ligand [3H][D-ala2, D-Leu5]enkephalin. ICI 154129 did not significantly influence the effects of ethanol in the behavioural experiments. Ethanol did not significantly change the binding parameters whether saturation or competition was measured in the receptor binding experiments. Thus, there was no evidence that the enkephalinergic system mediated the acute ethanol effects.