Hypothalamic aggression area under serotonergic control in mouse-killing behaviour of rats

Abstract

The serotonergic system participates in the modulation of aggressive behaviour. We examined the neuronal substrate underlying serotonergic control of aggressive behaviour in rats using a transplantation technique. Fetal serotonergic neurons transplanted into the hypothalamus restored inhibition of mouse-killing behaviour (muricide), in rats with raphe lesions induced by a serotonergic neurotoxin, 5,7-dihydroxytryptamine. Immunohistochemical and neurochemical studies indicated that the recovery of serotonergic innervation in the lateral hypothalamic area by the raphe grafts brought about the inhibition of muricide. The extension of serotonergic fibres into the lateral hypothalamic area from the grafted serotonergic neurons is strongly related to inhibition of muricide. These results indicate the possibility that serotonergic neurons regulate muricide through the inhibition of the activity of the lateral hypothalamic area neurons.

Induction of Fos-Like Immunoreactivity in the Lateral Hypothalamic Area of the Rat After Muricide

“…Microinjection of a specific serotonergic neurotoxin, 5,7-dihydroxytryptamine (5,, into the LHA significantly increased the incidence of muricide [5][6][7]. We previously reported that fetal serotonergic neurons transplanted into the rat hypothalamus restored inhibition of muricide that have been induced by lesioning with 5,7-DHT injection into the dorsal raphe nucleus (DRN) and medial raphe nucleus (MRN), origins of forebrain serotonergic innervation [8]. This result may suggest that serotonergic neurons regulate muricide by modulating the activity of the LHA neurons.…”