An examination of the effects of stimulant and depressant drugs on escape/avoidance conditioning in strains of rats selectively bred for emotionality/non-emotionality: a multivariate analysis of the effects of drugs on conditioned avoidance responses and intertrial activity

Abstract

The effects of increasing doses of amphetamine, sodium amytal, adrenaline and methylpentynol on 200 rats of the Maudsley Reactive and Non-Reactive strains were analyzed multivariately for scores of conditioned avoidance and intertrial crosses in an automatic shuttle box. The “dispersion” of the treatment, strains and dose groups was analyzed by use of a canonical analysis variance technique. Subsequently 2 “vectors” emerged; the first vector was denned as “conditionability” and the second “resistance to irrelevant activity”. An analysis of the vector scores revealed that the central stimulant and autonomic depressant drugs facilitated and the central depressant and autonomic stimulant drugs reduced the levels of conditionability but failed to affect the resistance to activity. The analysis of strain differences showed that the Non-Reactives were comparatively highly conditionable because of their lower resistance to activity. Further, it was only the Non-Reactive strain which differentiated the drug groups on both vectors; the Reactives were susceptible only to autonomic drugs. The treatment × dose interaction produced different dose-response relationships on both vectors.