Perivascular Neurotransmitter Regulation of Cerebral Blood Flow

Cerebral circulation is regulated by two principal systems: autonomic and sensory nerves from cranial ganglia and intrinsic innervation of the cerebral microcirculation. The sympathetic innervation originates from the superior cervical ganglion and stores noradrenaline and neuropeptide Y. It has a role in the extreme limits of the autoregulation. The parasympathetic innervation of the brain circulation originates in the sphenopalatine and otic ganglia. This system stores acetylcholine, vasoactive intestinal peptide, pituitary adenylate cyclase-activating peptide, and nitric oxide synthase (NOS). The sensory fibers, involved in cranial pain syndromes, originates in the trigeminal ganglion and stores calcitonin gene-related peptide, substance P, neurokinin A, NOS, and nociceptin, inter alia. Besides these, the intracerebral microcirculation (small arterioles, capillaries, and venules) forms, with the surrounding glial cells and intracerebral neurons, a neurovascular unit that may regulate the cerebral microcirculation.