Lesion of the dorsal raphe nucleus induces supersensitivity to serotonin in isolated cat middle cerebral artery.

Simultaneous lesions of dorsal and median raphe nuclei were induced after 15 days postjunctional supersensitivity to serotonin in isolated segments of cat middle cerebral artery. The same result was obtained when only the dorsal raphe nucleus was destroyed. The lesion of the median raphe nucleus brought about an increased contractile response to serotonin only at the three first doses used. The contractile response to noradrenaline was unaffected by these treatments. These results suggest the existence of a serotonergic innervation of the cat middle cerebral artery whose main origin might be the dorsal raphe nucleus.