The effect of lesions of dorsal or median raphe nucleus on rat behavior.

The effect of lesion of the dorsal raphe nucleus (DRN) or median raphe nucleus (MRN) on the locomotor activity, open field performance, and reactivity to noxious stimulus was tested in rats. During the first 7 days after the lesion, the rats with lesioned DRN showed higher basal and explorative locomotor activity than the rats with MRN lesions. The lesion of DRN increased the open-field performance and reactivity to pain. The results of tests carried out on the rats with MRN lesions were similar as in control rats. The results indicate that the different behavioral effect of lesions of DRN and MRN reffects differences in the functions of these two raphe nuclei.