Thigmotaxis as a test for anxiolytic activity in rats.

It has been suggested that "phylogenetically prepared fear reactions" may be useful behavioral assays of the effects of anxiolytic agents. In the present experiments, rats' natural proclivity to stay near the perimeters of a novel environment (i.e., thigmotaxis) was suppressed by anxiolytic agents (diazepam 1-5 mg/kg; chlordiazepoxide 1-10 mg/kg; pentobarbital 1-10 mg/kg), with a relative potency that was similar to their relative potency in the treatment of human anxiety. Furthermore, when effects on general activity were factored out using analysis of covariance, the test also showed some degree of drug-class specificity, since neither d-amphetamine, morphine, nor chlorpromazine produced this anti-thigmotaxic effect. These results support an earlier report that thigmotaxis may be a useful test for anxiolytic activity in rats.