The expression and activation of matrix metalloproteinase-1 after subarachnoid haemorrhage in rats

Background. Collagen lattice contraction has been reported as another aspect of the pathogenesis of cerebral vasospasm after subarachnoid haemorrhage (SAH). Recently, some authors have suggested that matrix metalloproteinase-1 (MMP-1) plays an important role in collagen lattice contraction. Therefore, this study aimed to clarify a role of MMP-1 during cerebral vasospasm in a rat SAH model. Method. We used a single-SAH model in rats and assessed the basilar arteries (BAs) at 30 minutes and on 2 days after SAH by cross-sectional area measurement and other histological parameters. Immunohistochemistry and Western blot analysis were used to quantify MMP-1 expression and activation. Results. BAs in rats significantly exhibited severe cerebral vasospasm at 30 minutes after SAH and moderate vasospasm on Day 2. The immunohistochemistry and Western blotting performed in BAs of rats demonstrated that both expression and activation in MMP-1 peaked at 30 minutes after SAH and then declined to the control level. Conclusions. MMP-1 is expressed and activated in a parallel time course to the development of cerebral vasospasm in an experimental model of SAH.