Effects of activation of D1 dopamine receptors on extinction of a conditioned passive avoidance reflex and amnesia in aggressive and submissive mice.

The studies reported here demonstrate the relationship between the effect of activation of D1 dopamine receptors on the reproduction of a conditioned passive avoidance reflex during extinction and amnesia and the aggressive and submissive behavioral stereotypes. During extinction, the D1 receptor agonist SKF 38393 at a dose of 5 mg/kg given before acquisition of the conditioned reflex and on test day 12 suppressed the reproduction of the conditioned skill in aggressive mice and improved reproduction in submissive mice. The effects of activation of D1 receptors were also opposite relative to the stereotype in amnesia. In aggressive mice, SKF 38393 significantly decreased the resistance to amnesia characteristic of these animals; in submissive mice, SKF 38393 weakened the amnestic effects of the delay in the "dangerous" sector and restored memory traces. The possible mechanisms of the selectivity of the actions of D1 receptors in mice with alternative behavioral stereotypes in retaining memory traces related to aversive stimulation during extinction and amnesia are discussed.