INVOLVEMENT OF DOPAMINERGIC-NEURONS IN MOUSE-KILLING AGGRESSION IN RATS

The sites associated with dopamine neurons which produce mouse-killing aggression (muricide) were examined in the rat brain Muricide appeare d in 60-80% of rats after being fed a thiamine-deficient diet for 28 d ays. Microinjection of dopamine dopamine (500 ng/rat) into the olfacto ry bulb (OB) significant suppressed muricide, whereas injection into o ther brain areas failed to do so. The incidence of muricide after dopa mine injection was 40% at 5 min and 20% at 15-30 min. When 6-hydroxydo pamine (8 mu g/0.5 mu l), following pretreatment with desmethylimprami ne (25 mg/kg i.p.), was injected twice into the ventral tegmental area (VTA) or the olfactory bulb (OB) iii nonkiller mrs during thiamine-de ficient feeding, rite occurrence of muricide gradually increased over time. The present results suggest that degeneration of dopamine neuron s projecting from the VTA to the OB may be related to mouse-killing ag gression iii rats.