ABSTRACT
The current research aimed to investigate the role of hypoxia-inducible factor-1α (HIF-1α), aquaporin-4 (AQP-4), and matrix metalloproteinase-9 (MMP-9) in blood-brain barrier (BBB) dysfunction and cerebral edema formation in a rat subarachnoid hemorrhage (SAH) model. The SAH model was induced by injection of 0.3 ml fresh arterial, non-heparinized blood into the prechiasmatic cistern in 20 s. Anti-AQP-4 antibody, minocycline (an inhibitor of MMP-9), or 2-methoxyestradiol (an inhibitor of HIF-1α), was administered intravenously at 2 and 24 h after SAH. Brain samples were extracted at 48 h after SAH and examined for protein expressions, BBB impairment, and brain edema. Following SAH, remarkable edema and BBB extravasations were observed. Compared with the control group, the SAH animals have significantly upregulated expressions of HIF-1α, AQP-4, and MMP-9, in addition to decreased amounts of laminin and tight junction proteins. Brain edema was repressed after inhibition of AQP-4, MMP-9, or HIF-1α. Although BBB permeability was also ameliorated after inhibition of either HIF-1α or MMP-9, it was not modulated after inhibition of AQP-4. Inhibition of MMP-9 reversed the loss of laminin. Finally, inhibition of HIF-1α significantly suppressed the level of AQP-4 and MMP-9, which could induce the expression of laminin and tight junction proteins. Our results suggest that HIF-1α plays a role in brain edema formation and BBB disruption via a molecular signaling pathway involving AQP-4 and MMP-9. Pharmacological intervention of this pathway in patients with SAH may provide a novel therapeutic strategy for early brain injury.
Subject(s)
Aquaporin 4/metabolism , Brain Edema/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Matrix Metalloproteinase 9/metabolism , Subarachnoid Hemorrhage/metabolism , 2-Methoxyestradiol , Animals , Aquaporin 4/antagonists & inhibitors , Blood-Brain Barrier/drug effects , Blood-Brain Barrier/metabolism , Brain Edema/drug therapy , Brain Edema/pathology , Disease Models, Animal , Estradiol/analogs & derivatives , Estradiol/pharmacology , Hypoxia-Inducible Factor 1, alpha Subunit/antagonists & inhibitors , Laminin/metabolism , Male , Matrix Metalloproteinase Inhibitors/pharmacology , Minocycline/pharmacology , Occludin/metabolism , Rats , Rats, Sprague-Dawley , Subarachnoid Hemorrhage/drug therapy , Subarachnoid Hemorrhage/pathology , Tubulin Modulators/pharmacology , Zonula Occludens-1 Protein/metabolismABSTRACT
This study investigated the possible involvement of matrix metalloproteinase 9 (MMP-9) in cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) in rats. The CVS model was established by injection of fresh autologous nonheparinized arterial blood into the cisterna magna. Experiment 1 aimed to investigate the timecourse of the MMP-9 expression in the basilar artery after SAH. In Experiment 2, we chose the maximum time point of vasospasm (Day 3) and assessed the effect of SB-3CT (a selective MMP- 9 inhibitor) on the regulation of cerebral vasospasm. The cross-sectional area of basilar artery was measured by H&E staining and the MMP-9 expression was assessed by immunohistochemistry analysis. The elevated expression of MMP-9 was detected in the basilar artery after SAH and peaked on day 3. After intracisternal administration of SB-3CT, the vasospasm was markedly attenuated after blood injection on day 3. Our results suggest that MMP-9 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in this rat experimental model of SAH and that the administration of the specific MMP-9 inhibitor could prevent or reduce cerebral vasospasm caused by SAH.
Subject(s)
Matrix Metalloproteinase 9/metabolism , Subarachnoid Hemorrhage/complications , Subarachnoid Hemorrhage/enzymology , Vasospasm, Intracranial/complications , Vasospasm, Intracranial/enzymology , Animals , Basilar Artery/drug effects , Basilar Artery/enzymology , Basilar Artery/pathology , Heterocyclic Compounds, 1-Ring/administration & dosage , Heterocyclic Compounds, 1-Ring/pharmacology , Heterocyclic Compounds, 1-Ring/therapeutic use , Immunohistochemistry , Male , Rats , Rats, Sprague-Dawley , Subarachnoid Hemorrhage/drug therapy , Sulfones/administration & dosage , Sulfones/pharmacology , Sulfones/therapeutic use , Vasospasm, Intracranial/drug therapyABSTRACT
Melatonin has beneficial effects against early brain injury (EBI) by modulating cerebral oxidative stress after experimental subarachnoid hemorrhage (SAH); however, few investigations relate to the precise underlying molecular mechanisms. To date, the relation between melatonin and nuclear factor erythroid 2-related factor 2 and antioxidant responsive element (Nrf2-ARE) pathway has not been studied in SAH models. This study was undertaken to evaluate the influence of melatonin on Nrf2-ARE pathway in rats after SAH. Adult male SD rats were divided into four groups: (i) control group (n=18); (ii) SAH group (n=18); (iii) SAH+vehicle group (n=18); and (iv) SAH+melatonin group (n=18). The rat SAH model was induced by injection of 0.3mL fresh arterial, nonheparinized blood into the prechiasmatic cistern in 20s. In SAH+melatonin group, melatonin was administered i.p. at 150mg/kg at 2 and 24hr after the induction of SAH. Brain samples were extracted at 48hr after SAH. Treatment with melatonin markedly increased the expressions of Nrf2-ARE pathway-related agents, such as Nrf2, heme oxygenase-1, NAD(P)H:quinone oxidoreductase 1, and glutathione S-transferase α-1. Administration of melatonin following SAH significantly ameliorated EBI, including brain edema, blood-brain barrier (BBB) impairment, cortical apoptosis, and neurological deficits. In conclusion, post-SAH melatonin administration may attenuate EBI in this SAH model, possibly through activating Nrf2-ARE pathway and modulating cerebral oxidative stress by inducing antioxidant and detoxifying enzymes.
