Ethanol retains its ability to modify endogenous opiate system in aged rats.

The effect of chronic ethanol administration (8% in the drinking water for 28 days) on opiate receptor function at striatal level was studied in adult (3 months) and aged (24 months) male Sprague Dawley rats. The treatment produces supersensitivity of striatal delta opiate receptors which may be ascribed to an inhibitory effect of ethanol on endogenous opiate release. In contrast the affinity of mu receptors is decreased. These changes are qualitatively and quantitatively similar in young and old rats.