Dabigatran etexilate (DE), a direct-acting, oral inhibitor of thrombin, significantly reduces the risk of stroke compared with traditional anticoagulants, without increasing the risk of major bleeding. However, studies on the fate of cerebral tissue after ischemic stroke in patients receiving DE are sparse and the role of dabigatran-mediated reduction of thrombin in this context has not yet been investigated. Here, we investigated whether pretreatment with DE reduces thrombin-mediated pro-inflammatory mechanisms and leakage of the blood–brain barrier (BBB) following ischemic stroke in rats. Male Wistar rats received DE (15 mg/kg) or a vehicle solution 1 hour before transient middle cerebral artery occlusion (tMCAO) for 90 minutes. Infarct volume, neurologic outcome and intracranial hemorrhage (ICH) were determined after tMCAO. Thrombin generation was indirectly assessed by measuring thrombin/antithrombin III complex. Microvascular patency was evaluated histologically. Cytokine expression and immunoreactivity of cluster of differentiation (CD) 68 were examined to characterize inflammatory processes after pretreatment with DE. BBB integrity was examined by quantifying brain edema. Rats given DE revealed a significant reduction in infarct size without an increase in ICH and significant recovery of neurologic deficits compared to controls. Administration of DE decreased thrombin generation and thrombus formation, dampened the CD68-immunoreactivity and attenuated pro-inflammatory cytokine expression in the cerebral parenchyma ipsilateral to the ischemic lesion. BBB permeability was unaltered following treatment with DE. In summary, prophylactic anticoagulation with DE improves stroke outcome by reducing thrombin-induced inflammation and thrombus formation without increasing the rate of ICH.

Fingolimod (FTY720) reduces infarct volume and improves neurological deficits in different rodent stroke models by modulating inflammatory and immune processes. However, studies on FTY720 regarding its non-immunological efficacy on ischemic cerebral tissue are sparse. Here we investigated whether FTY720 has cytoprotective and restorative properties following ischemic stroke in mice. Male mice received FTY720 (1mg/kg) or a vehicle solution intraperitoneally immediately prior to transient middle cerebral artery occlusion (tMCAO; 30 min.) and 48 hours thereafter. Infarct volume was determined on T2-weighted magnetic resonance images on day 1 and 7 after tMCAO. Motor function was assessed by the ladder rung walking test using a foot fault score. Specific immunostainings were performed to quantify neuronal density, astrocytic reactivity, microvascular density and expression of synaptophysin in the cortical perilesional area on consecutive brain slices. The amount of brain-derived neurotrophic factor (BDNF) was examined using ELISA analyses. FTY720 treatment significantly reduced infarct volumes and motor deficits compared to controls. Neuronal survival, astrogliosis as well as synaptogenesis and BDNF expression in the penumbra of the infarcted cortex did not significantly differ between the treatment groups. Taken together, our data support the hypothesis that the key mode of FTY720 action in stroke is the reduction of microvascular thrombosis and not a direct effect at the neurovascular unit (NVU).

Deep brain stimulation of the mesencephalic locomotor region (MLR) improves the motor symptoms in Parkinson’s disease and experimental stroke by intervening in the motor cerebral network. Whether high-frequency stimulation (HFS) of the MLR is involved in non-motor processes, such as neuroprotection and inflammation in the area surrounding the photothrombotic lesion, has not been elucidated. This study evaluates whether MLR-HFS exerts an anti-apoptotic and anti-inflammatory effect on the border zone of cerebral photothrombotic stroke. Rats underwent photothrombotic stroke of the right sensorimotor cortex and the implantation of a microelectrode into the ipsilesional MLR. After intervention, either HFS or sham stimulation of the MLR was applied for 24 h. The infarct volumes were calculated from consecutive brain sections. Neuronal apoptosis was analyzed by TUNEL staining. Flow cytometry and immunohistochemistry determined the perilesional inflammatory response. Neuronal apoptosis was significantly reduced in the ischemic penumbra after MLR-HFS, whereas the infarct volumes did not differ between the groups. MLR-HFS significantly reduced the release of cytokines and chemokines within the ischemic penumbra. MLR-HFS is neuroprotective and it reduces pro-inflammatory mediators in the area that surrounds the photothrombotic stroke without changing the number of immune cells, which indicates that MLR-HFS enables the function of inflammatory cells to be altered on a molecular level.