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

Abstract

Serotonergic innervation in the lateral hypothalamic area (LHA) has been implicated in mouse-killing behavior, muricide, of rats. In the present study, functional activation of neurons in the LHA was demonstrated by immunohistochemistry of Fos-protein, a marker of activated neurons, following raphe lesion-induced muricide. Fos-protein induction was seen in the ventral part of the intermediate hypothalamic area (IHA) of the LHA in the muricide rat. Following raphe transplantation into the brain near the bilateral IHA, a significant decrease in the number of Fos-immunoreactive cells was observed in this area, coinciding with decreased muricide behavior. The present results suggest that the decline in Fos-protein expression in this area may be associated with the inhibition of this behavior.