Influence of chronic emotional stress on the behaviour in "open field" test of rats with different level of motor activity

Experiments were carried out on 41 Wistar mail rats with body weight of 180 - 200 g. It was shown that in 'open field' the rats differed in the level of motional activity. Independently from level of locomotion investigated groups of rats were dissimilar at the criterions for "emotionality" and latent period of go out from the centr of "field". Prolonged neurogen stress rendered various (modulating) influence on the behaviour of the rats in'open field' that was depended from their start level of activity. In the lowactive rats stress in the main activated the motional and searching components of behaviour against a background of some decrease of the acts of defecation. In the meanactive rats stress increased the frequency of rearing and strengthened excretion function and in the highactive of rats stress reduced the quantity of horizontal moving and lowered the thresholds of reactions of rats on the skin electrical stimulation, facilitated increase in these of rats the level of "emotionality". Direction of changes of the time go out from the centr of "field" in each tested group basically depended by its start indexes and on peak of stress action had reverse dependence. It is supposed that changes of behaviour of rats in the "open field" under corresponding intensity of stress may be caused as by neuroendokrine changes as by stress damage of brain structures.