Expression of high-mobility group box-1 (HMGB1) in the basilar artery after experimental subarachnoid hemorrhage.

It has been suggested that inflammatory damage may be involved in the pathogenesis of cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH). High-mobility group box-1 protein (HMGB1) has been identified as a potent proinflammatory mediator, and may trigger increases in other inflammatory cytokines. However, little is known about the role of HMGB1 in SAH-induced cerebrovascular inflammation. In this study, 48 male rats were assigned randomly to four groups: a control group, or SAH day 3, day 5, or day 7 groups. The animals in SAH day 3, day 5, and day 7 groups were subjected to injection of autologous blood into the cisterna magna twice, on day 0 and day 2, and were killed on days 3, 5, and 7, respectively. Cross-sectional area of the basilar artery was measured and the HMGB1 expression was assessed by immunohistochemistry and western blot analysis. The mRNA level of HMGB1 was also determined by reverse transcription polymerase chain reaction. The basilar arteries exhibited vasospasm after SAH which was most severe on day 3 and 5. Elevated expression of HMGB1 was detected after SAH and was highest on day 3 and 5. HMGB1 is increasingly expressed in parallel to the development of CVS in this rat experimental model of SAH. These results suggest that HMGB1 may be related to the CVS observed after SAH and HMGB1 may play a key role in the inflammatory response in CVS after SAH.