Schedule-induced ethanol dependence and phenobarbital preference.

Rats exposed to a daily 3-hr session of intermittent food delivery ingested physical-dependence-produced levels of 5% ethanol solution. Although this schedule induced a chronic, voluntary, daily overindulgence, this had no effect on 21-hr home-cage phenobarbital preference. The substitution of water for 5% ethanol during the daily 3-hr binge session did not change home-cage phenobarbital preference, which remained stable and similar to that of a control group of non-binging animals. This experiment and others indicate that physical dependence on ethanol does not play a major role in the maintenance of ethanol abuse or cross-abuse of the barbiturates.