Imatinib mesylate prevents cerebral vasospasm after subarachnoid hemorrhage via inhibiting tenascin-C expression in rats.
ABSTRACT Platelet-derived growth factor (PDGF) has been implicated in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH), but the mechanism remains unknown. The purpose of this study was to assess whether imatinib mesylate (imatinib), an inhibitor of the tyrosine kinases of PDGF receptors (PDGFRs), prevents cerebral vasospasm after SAH in rats, and to elucidate if tenascin-C (TNC), a matricellular protein, is involved in the mechanism. Imatinib (10 or 50 mg/kg body weight) was administered intraperitoneally to rats undergoing SAH by endovascular perforation, and the effects were evaluated by neurobehavioral tests and India-ink angiography at 24-72 h post-SAH. Western blotting and immunohistochemistry were performed to explore the underlying mechanisms in cerebral arteries at 24h post-SAH. Recombinant TNC was administered intracisternally to imatinib-treated SAH rats, and the effects were evaluated by neurobehavioral tests, India-ink angiography and immunohistochemistry at 24 h post-SAH. Both dosages of imatinib significantly prevented post-SAH neurological impairments and vasospasm at 24-72 h. SAH caused PDGFR-β upregulation, PDGFR activation, mitogen-activated protein kinase activation, and TNC upregulation in the spastic cerebral arteries, all of which were significantly suppressed by imatinib treatment. Recombinant TNC reversed the anti-vasospastic effects and protein expression changes by imatinib. This study suggests that imatinib prevents cerebral vasospasm at least partly via inhibiting the upregulation of TNC, implying that TNC may be a new therapeutic target for post-SAH vasospasm.