Selective effects of ethanol on opiate receptor subtypes in brain.

Large concentrations of ethanol in vitro decreased ligand binding to mu and delta opiate receptors in the frontal cortex of the C57BL mouse, but did not alter binding to kappa opiate receptors. Mu and delta receptors were equally sensitive to the inhibitory effect of ethanol. Since the effects of ethanol were significant only in large concentrations, ethanol may alter opiate binding through its membrane lipid-perturbing actions, and the selectivity of the effects of ethanol may reflect differences in the microenvironments of the opiate receptor subtypes in membranes. After chronic ingestion of ethanol by mice, in vivo, there was a selective decrease in the number of mu receptors in the frontal cortex. This change may result from indirect effects of ethanol on the opiate receptor and may contribute to specific central effects of ethanol.