Regulation of Genetic Aggression by Central Dopamine System - Plurality of Dopamine Receptor -

Two types of aggressive behavior were produced by selective breeding in ICR mimce. NC900 line mice exhibited high level of species-typical, isolation-induced aggression, conversely, NC100 line mice exhibited little aggression. The present study tested the hypothesis that these differences involved brain monoamine systems. Comparisons of microdissected samples from various brain regions showed that NC100 line mice had significantly lower concentrations of dopamine. DOPAC and HVA in the nucleus accumbens (NAB) and caudate nucleus (NCU) than NC900 line. Homogenate binding studies demonstrated that NC100 mice had significantly increased density of $D_1$ dopamine receptor, but not $D_2$ dopamine receptor in the caudate nucleus. These results support the hypothesis that central dopamine pathways play an important role in modulating the genetically selected differences in aggressive behavior, and of which intensity differs from TEX>$D_1$\;and\;$D_2$ dopamine receptors.