Effect of calcitonin gene-related peptide on delayed cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits

BACKGROUND: Calcitonin gene-related peptide (CGRP) is an intrinsic vasodilatory substance contained in perivascular nerve fibers of intracranial arteries. It is suggested that CGRP plays a role in cerebral vasospasm after subarachnoid hemorrhage (SAH). METHOD: An experimental SAH was produced by intracisternal injection of arterial blood in rabbits. The animals were treated with intrathecal administration of CGRP solution 3 days after SAH. The degree of vasospasm and the effect of CGRP were evaluated angiographically by measuring the basilar artery diameter. RESULTS: The basilar artery constricted to 73.0% of the pre-SAH values 3 days after SAH. Fifteen minutes after injection of 10^-10 mol/kg CGRP, the basilar artery dilated to 117.1% (n = 8), which was significantly larger than 67.1% in the vehicle group (n = 8) (p < 0.01). The significant vasodilatory effect of CGRP, compared with the vehicle group, lasted for 6 hours. CONCLUSIONS: Intrathecal administration of CGRP has therapeutic potential for treating cerebral vasospasm.