Pre- and postsynaptic mechanisms of the involvement of amygdaloid complex serotonin in the reproduction of a conditioned passive avoidance response in rats.

Serotonin metabolism and [3H]-serotonin radioligand receptor binding were studied in the amygdaloid complex of the rat brain at different stages of a conditioned passive avoidance response. Serotoninergic changes were specific for the process of reproduction of the conditioned response. The involvement of serotonin in the amygaloid complex during reproduction of memory traces consisted of a reduction in its postsynaptic receptor binding. The serotonin level in the amygaloid complex did not change, while changes in serotonin metabolism detected during reproduction of the conditioned avoidance response were associated with an increase in its deamination by monoamine oxidase and an increase in the active transport of 5-hydroxyindoleacetic acid from nerve terminals.