Behavioral characteristics of two rat strains differing in sensitivity to the cardiotoxic effect of isoprenaline

Behavioral pattern was studied in two inbred strains of rats which have different responses to stress. These strains were originally developed from a randomly bred Wistar rat colony, according to high or low myocardial cells sensitivity to cardiotoxic effect of isoprenaline. One strain is very sensitive to isoprenaline cardiotoxicity (IS = isoprenaline sensitive) the other strain is more resistant (IR = isoprenaline resistant). In the IR strain the immobilization immersion stress causes high incidence of gastric ulcers, while the IS strain is prone to heart pathology. In this communication we report the differences in behavior of these two rat lines in three tests: open field, intruder's test and Porsolt's forced swimming test. The IS animals were passive and anxious in open field test, submissive in intruders test and they showed more floating time in Porsolt's forced swimming test. The IR rats were active, aggressive and dominant.