Production of physical dependence on ethanol by a short drinking episode each day.

A 3-hr schedule-induced ethanol polydipsia regimen was used in rats to elevate blood alcohol concentration to a single intoxicating peak each day. After 3 weeks, and again after 3.5 months, animals were tested for the presence of physical dependence by exposure to a brief auditory stimulus (key shaking) at 7 and 11 hr after ethanol polydipsia. Withdrawal signs were observed only at 11 hr when blood ethanol levels had returned to zero. No such signs were observed when animals were made water polydipsic. While sufficient, continuous elevation of blood ethanol concentration is not necessary for the development of a demonstrable physical dependence. A limited daily ethanol binge was sufficient.