Depletion of calcitonin gene-related peptide in perivascular nerves during acute phase of posthemorrhagic vasospasm in the rabbit.

The behaviour of various neuropeptides during early and late vasospasm following experimental subarachnoid hemorrhage has been investigated by several authors. Recently, a reduction of the content of vasodilatory neuropeptides (vasodilatory intestinal peptide, substance P and calcitonin gene-related peptide) has been demonstrated in the perivascular nerves of cerebral arteries after few days from induction of experimental subarachnoid hemorrhage. In the present immunohistochemical study, the authors investigated secretion and expression of CGRP a few minutes after injection of autologous blood into the cisterna magna of the rabbit. The authors propose that the marked decrease of calcitonin gene-related peptide immunoreactivity in the perivascular nerves, observed after experimental subarachnoid hemorrhage, is due to compensatory secretion of the peptide.