Changes of calcitonin gene-related peptide-like immunoreactivity in cerebrovascular nerve fibers in the dog after experimentally produced subarachnoid hemorrhage.

After producing a model of subarachnoid hemorrhage (SAH) by a single injection of fresh autologous arterial blood into the cisterna magna in the dog, we immunohistochemically examined changes of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in perivascular nerve fibers in the large pial arteries by using whole mount preparations. CGRP-LI in cerebrovascular nerve fibers was suppressed after SAH. The suppression was first detected on the 3rd day after SAH, and was most marked during the 7th to 14th day after SAH. CGRP-LI, however, recovered to a normal level by the 42nd day after SAH.