Effects of repeated ethanol administration in the plus maze; a simple model for conditioned abstinence behaviour

Classical conditioning is considered to be an important factor in drug dependence. Exposure to an environment in which alcohol has been repeatedly consumed may produce feelings of anxiety and dysphoria in a currently abstinent patient, and may precipitate relapse drinking. The present study modeled this process, by repeatedly exposing mice to an elevated plus maze after ethanol administration. When ethanol injections and maze exposure were repealed for 9 days, and the ethanol injections replaced by saline on the tenth day, mice consistently exhibited a characteristic behaviour pattern, with increased stretched attend postures and proportion of time spent in the central square. This behaviour was different from that previously seen during withdrawal from ethanol, and was not observed when repeated injections of ethanol were given either without, or after, maze exposure. Thus the characteristic behaviour pattern appeared to be contingent on the animals being repeatedly exposed to the maze environment while under the influence of ethanol. In particular, the reduction in stretched attend postures produced by acute ethanol, the tolerance to this behaviour seen after repeated ethanol and the increase in it after replacement of ethanol by saline, are consistent with the pattern predicted for a behavioural response to the absence of ethanol, conditioned to the environment of the maze.