Intracerebral microdialysis studies of Sprague–Dawley rats showed that acquisition of a conditioned reflex fear reaction (combination of a conditioned sound signal CS+ and an unavoidable electrocutaneous stimulus) was accompanied by an increase in the level of extracellular serotonin in the medial prefrontal cortex. Administration of the selective serotonin transporter inhibitor fluoxetine (1 μM) into the medial prefrontal cortex during acquisition of the conditioned reflex fear reaction magnified the increase in extracellular serotonin in these structures seen during this test and, secondly, strengthened freezing of the animals at 1 day (the measure of fear) in response to the differential signal CS–, not associated with pain stimulation (test for generalization of fear), but had no effect on freezing in the same animals in response to the conditioned stimulus CS+, previously combined with pain stimulation (test for expression of the fear reaction). These data provide the first evidence that stimulation of the serotoninergic system of the medial prefrontal cortex during acquisition of a condition reflex fear reaction promotes subsequent generalization of this conditioned reflex reaction without affecting its formation.
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Translated from Zhurnal Vysshei Nervnoi Deyatel’nosti imeni I. P. Pavlova, Vol. 69, No. 3, pp. 343–353, May–June, 2019.
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Saulskaya, N.B., Marchuk, O.E. Inhibition of Serotonin Reuptake in the Medial Prefrontal Cortex during Acquisition of a Condition Reflex Fear Reaction Promotes Formation of Generalized Fear. Neurosci Behav Physi 50, 432–438 (2020). https://doi.org/10.1007/s11055-020-00918-x
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DOI: https://doi.org/10.1007/s11055-020-00918-x