EN
In recent years we have elaborated an animal model to examine the neurochemical background of differences in the individual responses to conditioned aversive stimuli, using the strength of a rat contextual fear test, as a discriminating variable: low responders (LR), i.e. rats with duration of a freezing response one standard error, or more, below the mean value and high responders (HR), i.e. rats with duration of a freezing response one standard error, or more, above the mean value. It was found that 1.5 h after a testing session of contextual fear test, the LR animals showed a higher density of 5-HT1A and glucocorticoid immunoreactivity-expressing cells (GRsir) in the cortical M2 area and hippocampal dentate gyrus as well as an increased number co-expressing 5-HT1A /GRs-ir in the same areas. The HR rats had a signifi cantly higher concentration of 5-HT1A and GRs-ir in the basolateral amygdala. The present data add more arguments for the neurobiological background of differences in individual responses to aversive conditioned stimuli.