Opioid-mediated acute responses to alcohol: ethanol potentiates opioid actions on the guinea pig ileum.

Acute administration of ethanol can potentiate the inhibitory effects of exogenously administered opioids on release of acetylcholine from the guinea pig's enteric nervous system. Ethanol also appears to inhibit the release of enteric substance P by enhancing the inhibitory action of simultaneously released endogenous opioids. One consequence of this mechanism of action is that those states that result in the activation of opioid-containing systems, such as stress, might also be the conditions under which the opioid component of the actions of ethanol are the most pronounced.