A comparative analysis of learning and exploratory behavior of rats with varying resistance to stressor influences and the level of brain monoamines.

Experiments have demonstrated that Wistar rats resistant (R) to acoustic stimulation differed from nonresistant (NR) rats by elevated exploratory activity under the condition of moderate stress in an open field test, by heightened reactivity to sensory stimuli of varying modality (somatosensory, visual, and olfactory), and by a reduced level of exploratory behavior in a burrow chamber. The rats of the R group differ from the NR animals by a greater capacity to learn a goal-directed reaction and by a lower capacity for discrimination of emotionally distinct influences. The results of a biochemical analysis of the content of biogenic amines in particular brain structures revealed in the resistant rats an increase in the level of norepinephrine, and in the non-resistant rats, a higher level of dopamine and serotonin.