Involvement of dopaminergic systems in the functional specialization of brain areas during formation of aggressive and submissive behavior in mice

In addition to its common activating action, the DA system is involved in the functional specialization of the brain areas which participate in the expression of discrete behavioral components. The evidence for different levels of activity of the mesocortical DA system in aggressive and submissive mice were obtained. In C57BL/6J mice, confrontations produced simultaneous increase in the extracellular DA content and its release from the nerve terminals in the nucleus accumbens and frontal cortex, while an elevation of the HVA concentration in these structures was found only in submissive mice. After 20 encounters, the habituation of animals to the repeated stress exposures and conditioning developed. Activation of the DA metabolism (increase in the DOPAC level and DOPAC/DA ratio) in the hippocampus was observed only in aggressive mice after 20 days of confrontation, when the extinction of the information novelty leading to aggression had been already accomplished. Our findings suggest the predominance of the role of the mesolimbic DA system, in particular, of its mesoaccumbens link, in the extinction of the information novelty in aggressors. A role of the mesocortical DA system in realization of the submissive behavior patterns, stress reactions, conditioned defensive behavior, anxiety-related behavior, and in modulation of the anxiety response to social stimuli is considered.