Immunohistochemical demonstration of vasopressin nerve fibers in the cerebral artery.

Vasopressin-immunoreactive nerve fibers were demonstrated in the cerebral pial arteries by peroxidase immunohistochemistry. In the large pial artery (proximal part of the middle cerebral artery), they ran longitudinally to the long axis of the vessel. They ran in a spiral pattern in the distal part of the middle cerebral artery. Even in small arteries, vasopressin nerve fibers were found arranged in a longitudinal fashion. The present morphological data suggest that vasopressin nerve fibers in the cerebral artery may play a role in cerebral circulation.