gms | German Medical Science

Objective: Spontaneous intracerebral hemorrhage (ICH) is a leading cause of disability and mortality. Perihematomal thrombin expression plays a pivotal role in edema formation and neuronal death. It is hypothesized that direct thrombin inhibitors (DTI) such as Argatroban mitigate secondary injury development after ICH. In our study we analyze the effects of systemic Argatroban treatment on neuronal injury and neurological outcome in an ICH mouse model.

Methods: We established a stereotaxic ICH model using C57BL/6 mice. 30 µl autologous blood was injected into the right basal ganglia. Intra-operative monitoring included intracranial pressure (ICP), cerebral blood flow (CBF) and blood pressure (BP) measurment. Argatroban (9mg/kg bodyweight) was injected 1 hour after surgery. Neuroscore and Rotarod testing were performed to detect neurological deficits. Mice were euthanized 24h and 72h after ICH. Frozen sections were stained with hematoxylin and eosin to evaluate size and localization of ICH. Immunohistochemistry was used to detect perihematomal thrombin. Immunofluorescence staining for NeuN and GFAP were used to evaluate parenchymal damage.

Results: The ICP increased during ICH induction with peak values of 54.0+-10 mmHg in the blood group and remained at 8.1+-0.6 mmHG in sham operated animals. CBF dropped to 32.0%+-8.1% of baseline in blood- and remained unaltered in sham animals. ICP and CBF returned to baseline values within 30 min after ICH. Perilesional thrombin expression increased by 4.24+-0.50-fold (p < 0.05) 24h after ICH. Perihematomal NeuN immunoreactivity was decreased in animals injected with DTI (3.79+-1.34-fold, 34.4+-0.21% area (p=0.001)) and those injected with saline (4.32+-2.26-fold, 31.8+-0.11 % area (p=0.001)). After 72h, mice receiving the DTI showed significantly lower neuronal loss, compared to mock injected animals (56+-19.2% area vs 107+-24.5%; p=0.0013). GFAP expression was increased in animals receiving the DTI 72h after ICH (0.99+-0.55% area vs 1.88+-0.83%; p < 0.005). Both groups performed similar using the rotarod performance test (saline: 92.5+-5s; DTI: 95+-3s; p < .0001). Likewise, no statistically significant disparities were detected using the neuroscore.

Conclusion: Systemic administration of Argatroban starting 1 hours after ICH significantly reduced neuronal damage 3 days after ICH. At the same time, GFAP expression increased indicating developing astrogliosis as potential protective mechanism to restrict the focus of neuronal damage.