Role of basic fibroblast growth factor in the course of cerebral vasospasm in an experimental model of subarachnoid hemorrhage

The goal of this study was to investigate the relationship between basic fibroblast growth factor (bFGF) and the course of cerebral vasospasm after subarachnoid hemorrhage (SAH), using an immunohistochemical method. Female Sprague-Dawley rats were sacrificed by perfusion fixation 10 min, 6 h, 1, 2, 3, 4, 7 or 14 days after a single intracisternal injection of fresh autologous arterial blood. Morphometric analysis of lumen cross-sectional areas of blood vessels were determined by computerized image analysis. Results were expressed as percent lumen patency, defined as the ratio of the area of vessel patency in SAH rats to the area of patency in control rats. An immunohistochemical analysis against bFGF was performed using the avidin-biotin-peroxidase technique. The immuno-reactivity of bFGF was observed with the aid of a light microscope and semiquantitatively graded. Basilar arterial spasm was greatest 10 min after SAH (mean decrease: 67.1% of the control values; p < 0.001). Subsequently, there was a significant degree of spasm of the artery for three days after SAH, followed by full recovery at day 4. A slight increase in immunoreactivity was observed in the intima only at 10 min and one day after SAH. In the media, immunoreactivity showed a biphasic pattern; a significant increase in immunoreactivity was observed at 10 min that persisted for two days after SAH. At three days after SAH, immunoreactivity in the media returned to the control level, but then gradually increased significantly to reach a maximum at 14 days after SAH while the vascular dimensions were normal. Immunohistochemical analysis failed to show a direct relationship between bFGF and the course of cerebral vasospasm in this rat single-hemorrhage model. However, the late phase upregulation of bFGF might lead to the vascular angiopathy, fibrosis or hyperplasia during the chronic stage of SAH.