Intraspecific aggressiveness after lesions of midbrain raphe nuclei in rats

Serotonin-depleting lesions of midbrain raphe (extensive lesions located within dorsal and partly median raphe muclei) induced intraspecific agressiveness in grouped Wistar male rats but failed to increase mouse-killing behaviour. Rats which had lesions in the lateral midbrain did not display intraspecific aggression nor mouse-killing activity. These animals showed unchanged levels of both serotonin and noradrenaline in the forebrain.