Effects of various drugs on behavioral contrast using a double-crossover procedure

Abstract

A behavioral contrast method that yields reliable and durable effects in both the positive and negative directions in the same animals was used to test the effects of sodium amylobarbitone, maprotiline, chlordiazepoxide, pargyline, diazepam, imipramine, chlorpromazine, and d -amphetamine. A double-crossover design was used to control for possible trends throughout the experiments. A new graphical method is described that allows one to present all the relevant within-day and between-day data in a single display and to detect changes in size of positive and negative contrast. The method, originally designed as a possible test of antidepressant agents, revealed no significant effects on contrast of the three antidepressant agents, with the exception of a small but significant increase in positive contrast with maprotiline. The two minor tranquilizers, chlordiazepoxide and diazepam, as well as amylobarbitone, produced significant reductions in both positive and negative contrast, although the effects were more conspicuous on negative than on positive contrast. The results suggest that the minor tranquilizers (including amylobarbitone) may be more adequately described as having an emotional “flattening” effect rather than a restricted antianxiety or antifrustration action.