Astaxanthin reduces matrix metalloproteinase-9 expression and activity in the brain after experimental subarachnoid hemorrhage in rats

We have previously shown that astaxanthin (ATX) reduces the blood-brain barrier (BBB) disruption and neurovascular dysfunction following subarachnoid hemorrhage (SAH) insults. However, the underlying mechanisms remain unclear. It is known that the matrix metalloproteinases (MMPs), especially matrix metalloproteinase-9 (MMP-9) plays a crucial role in the pathogenesis of secondary brain injury after SAH. And ATX has the ability to regulate MMP-9 in other models. Herein, we investigated whether ATX could ameliorate MMP-9 activation and expression in a rat model of SAH. A total of 144 rats were randomly divided into the following groups: control group (n=36), SAH group (n=36), SAH+vehicle group (n=36), and SAH+ATX group (n=36). The SAH model was induced by injection of 0.3 ml autologous blood into the prechiasmatic cistern. ATX (20 mu l of 0.1 mmol) or vehicle was administered intracerebroventricularly 30 min after SAH induction. Mortality, neurological function, brain edema and blood-brain barrier (BBB) permeability were measured at 24 and 72 h after SAH. Biochemical and zymographic methods were used to analyze MMP-9 expression and activity in brain samples. Immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining were also evaluated at 24 h. Our data indicated that ATX could significantly reduce the expression and activity of MMP-9, leading to the amelioration of brain edema, BBB impairment, neurological deficits and TUNEL-positive cells at 24 h but not 72 h after SAH. The ATX-mediated down-regulation of MMP-9 was correlated with the decreased levels of IL-1 beta, TNF-alpha, oxidative stress, activated microglia and infiltrating neutrophils. These results suggest that the neurovascular protection of ATX in SAH is partly associated with the inhibition of MMP-9 expression and activity. (C) 2015 Elsevier B.V. All rights reserved.