Abstract

Ischemic stroke is a leading cause of mortality and long-term disability, with the peri-infarct zone being critically dependent on the response of glial cells, particularly astrocytes. Thrombin, a serine protease, is rapidly generated following cerebral ischemia and hemorrhage, suggesting a pivotal role in the acute phase of injury. This study investigated the cellular and molecular effects of thrombin on cultured rat astrocytes subjected to oxygen-glucose deprivation (OGD), an in vitro model of ischemia. Our primary objective was to determine how thrombin modulates astrocyte viability and morphology under ischemic stress, with a focus on membrane-associated signaling pathways. Astrocytes were exposed to varying concentrations of thrombin (1 nM to 100 nM) before, during, or after OGD. We found that low concentrations of thrombin (e.g., 10 nM) conferred a significant protective effect against OGD-induced cell death, maintaining mitochondrial function and reducing the release of lactate dehydrogenase. Conversely, high concentrations (e.g., 100 nM) exacerbated OGD-induced cytoskeletal damage, specifically potentiating actin stress fiber formation, suggesting a dose-dependent, dual role. This protective effect is likely mediated through the activation of Protease-Activated Receptor 1 (PAR-1) and subsequent downstream signaling cascades that regulate cell survival and cytoskeletal integrity. These findings highlight thrombin as a critical, concentration-dependent modulator of astrocyte response to ischemia, offering a potential therapeutic target for mitigating secondary injury following stroke.