Studies of the interaction between behavioral stereotypes and the effects of activation of presynaptic dopamine receptors during extinction and amnesia in mice.

The involvement of presynaptic dopamine receptors in the retention of a conditioned passive avoidance reflex through extinction and amnesia was studied in C57BL/6J mice selected in a 20-day aggressive conflict test for aggressive and submissive behavioral stereotypes. These experiments showed that in aggressive mice, activation of presynaptic receptors with the agonist (+)3-(3-hydroxyphenyl)-N-n-propylpiperidine [(+)3PPP] at a dose of 2 mg/kg degraded learning, significantly decreased the retention time of the acquired conditioned habit in extinction, and increased the effect of an amnesia-inducing treatment. Mice showing submissive behavior in daily confrontations with aggressors responded to administration of (+)3PPP with long-lasting reproduction of the conditioned passive avoidance reaction during extinction and showed no changes in the development of amnesia. These data on the relationship between the effects of activating presynaptic dopamine receptors in reproduction of the memory trace in conditions of trace disruption on the one hand and behavioral status on the other are assessed from the point of view of different basal levels of dopaminergic system operation in aggressive and submissive mice.