Roles of cerebrovascular innervations and their neurotransmitters in various pathological conditions of central nervous system

The concept of neurogenic control of the cerebral circulation began to develop only as recent as the middle of the 20^th century, when it was elucidated that the cerebral blood vessels are supplied by a very dense plexus of adrenergic nerves innervating the vascular bed. After then, already in the course of several decades, more than ten types of neurotransimitters including acetylcholine, serotonin, substance P, and calcitonin gene-related peptide, etc., have been observed in these nerves. To determine the origins and pathways of cerebrovascular parasympathetic nerves and sensory nerves, retrograde axonal tracing with immnohistochemstry has been studied. The cerebrovascular parasympathetic nerves originated 1) in the sphenopalatine ganglion (SPG), and 2) from the internal carotid ganglion, and also 3) from the otic ganglion. While the cerebrovascular sensory nerves originated 1) in the trigeminal ganglion (TG), and 2) from the internal carotid ganglion, and also 3) from the upper cervical dorsal root ganglia. The neurogenic cerebrovascular vasodilatation was demonstrated in vivo, by the electrical stimulation of the cerebraovascular branches of TG or SPG. This vasodilatation was attenuated not by anticholinergic agents but triptans as well as anti-CGRP agents. This implicates the mechanism of pathological neurogenic inflammation and vasodilatation during the migraine attacks.