[Peptidergic innervation of the cerebral blood vessels--an immunohistochemical study]

By an immunohistochemical technique, vasoactive polypeptide (VIP)-and substance P-containing nerve fibers are observed in the cerebral blood vessels. VIP-containing nerve fibers distribute in a spiral pattern, similar to the muscle cell distribution pattern. Under an electron microscopic observation, VIP-immunoreactive terminals lie just near to a muscle cell in the inner layer of the adventitia. In contrast, substance P-containing nerve fibers show a meshwork pattern in the outer layer of the adventitia. In combination of acetylcholinesterase (AChE) staining and VIP immunohistochemistry, AChE-positive and VIP-immunoreactive nerve fibers reveal almost same distribution in the same specimen. The present data suggest that VIP-containing nerve fibers may play a role of smooth muscle control of the blood vessels, while substance P-containing nerve fibers may not take part in muscle control.