Fluprazine inhibits intermale attack and infanticide, but not predation in male mice

The effects of fluprazine (1, 2, and 5 mg/kg) on intermale attack, infanticide and predation (insect larvae) by male mice were assessed. Fluprazine dose-dependently inhibited attacks by males on conspecific intruders and genetically unrelated mouse pups. However, predatory attack on insect larvae was unaltered by any dose of the compound. Thus the neurohumoral substrates underlying intraspecific attack and pup killing may be similar to each other, but different from those modulating predatory attack and prey killing. These data support the hypothesis that male infanticide is a form of intraspecific aggression and not an expression of intraspecific predation (cannibalism). Drug-induced stimulation of paternal behavior in some previously infanticidal males suggests that serotonergic substrates may also be involved in the natural mechanisms which mediate the inhibition of infanticide and promote parental care.