Changes of vasoactive intestinal polypeptide-like immunoreactivity in cerebrovascular nerve fibers after subarachnoid hemorrhage: an experimental study in the dog.

A model of subarachnoid hemorrhage (SAH) was experimentally produced in the dog by a single injection of fresh autologous arterial blood into the cisterna magna, and then changes of vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI) in perivascular nerve fibers were examined immunohistochemically in the proximal portions of the middle cerebral artery. Perivascular nerve fibers with VIP-LI were markedly decreased in number during the 1st week after SAH. However, they were gradually reincreased during the 2nd to 9th week after SAH to be recovered to the normal level on the 63rd day after SAH.