Demonstration of neuropeptide containing nerves and vasomotor responses to perivascular peptides in human cerebral arteries.

A rich supply of nerve fibers containing neuropeptide Y-like (NPY-LI) and tyrosine hydroxylase-like immunoreactivity was seen in human cerebral arteries, arterioles and veins. Only a sparse supply of vasoactive intestinal polypeptide (VIP-LI), substance P (SP-LI), and calcitonin gene-related peptide (CGRP-LI) was demonstrated in the walls of human cerebral vessels. In isolated ring segments of human cerebral arteries, NPY and noradrenaline caused vasoconstriction but did not potentiate each other. VIP, peptide histidine methionine, SP, neurokinin A, and CGRP relaxed arteries precontracted by prostaglandin F2 alpha. The degree of innervation and the vasomotor responses are discussed in relation to migraine pathophysiology.