Psychophysiological profiles of the Roman strains of rats.

Male rats of the Roman High and Roman Low Avoidance strains were submitted to four principal behavioral tests: food-motivated acquisition of bar-pressing in Skinner box, delayed reinforced alternation, locomotor activity in a "multibox apparatus," conditioned suppression, and two biological measures: blood pressure and brain octopamine level. Performances of RLA and RHA rats were significantly different in each behavioral test. Blood pressure was higher in RHA, but the difference only approached the 0.05 threshold. As previously reported, brain octopamine levels of RHA rats were significantly higher than those of RLA. A multivariate treatment (analysis of correspondences) was applied to the data of 10 behavioral tests. The main factor extracted by this treatment clearly separated the two strains. Among the variables which best differentiate RHA and RLA rats, several do not involve stress (working memory, acquisition of bar-pressing, and locomotor activity).