5-Hydroxytryptophan uptake in indoleaminergic nerve fibers within rat cerebrovascular tree

Using a fluorescence histochemical method we found that the precursor in the synthesis of serotonin, 5-hydroxytryptophan (5-HTP), is taken up by a population of nerve fiber-like structures, presumably indoleaminergic in nature, within the wall of cerebral arteries. These findings may indicate that the therapeutic action of 5-HTP in the management of some types of headache is determined by a direct peripheral action on cerebral blood vessel.