Changhong Ren

Remote ischemic post-conditioning reduced brain damage in experimental ischemia/reperfusion injury

Abstract Objectives: To determine the protective effects of remote post-conditioning on ischemic brain lesions caused by middle cerebral artery (MCA) occlusion in rats. Methods: A total of 54 animals were used in this present study. An ischemic stroke model was generated by 90-minute occlusion of right MCA (n = 42). Twelve rats were used as control for studying edema and blood-brain barrier (BBB) integrity. Remote post-conditioning was conducted immediately after MCA occlusion in the bilateral lower limb by occluding and releasing the femoral artery for three cycles; each occlusion and release lasted for 10 minutes. After 24 hours of reperfusion, the cerebral infarct volumes were quantified by 2,3,4-triphenytetrazolium-chloride, brain water content was determined by dry/wet weight method, and damage to the BBB was determined by Evans blue extravasation. Results: Remote post-conditioning significantly reduced brain infarct damage (P<0·0001). Brain edema was significantly (P<0·01) reduced after stroke in the remote post-conditioning group. BBB leakage was significantly reduced in the remote post-conditioning group when compared to the control ischemic groups (P<0·05). Conclusion: These results provide evidence that remote post-conditioning, which was initiated after ischemia and before reperfusion, protects against brain injury in experimental ischemic stroke.

Effect of remote ischemic postconditioning on an intracerebral hemorrhage stroke model in rats

Abstract Background and purpose: While recent studies suggest that remote ischemic postconditioning (RIP) therapy may be of benefit to patients with acute ischemic stroke, RIP’s effects on intracerebral hemorrhage (ICH) still remains unclear. In the present study, the use of RIP in a rat model ICH was investigated to elucidate any potential beneficial or detrimental effects as determined by motor testing, blood brain barrier integrity, and brain water content, as well as aquaporin-4 (AQP-4) and matrix metalloproteinase-9 (MMP-9) expression. Methods: ICH was induced in Sprague–Dawley rats and they were randomized into either a control (nu200a=u200a24) or RIP treatment (nu200a=u200a24) group. RIP was performed by repetitive, brief occlusion and release of the bilateral femoral arteries. Functional outcome in each group was assessed by neurologic deficits on vibrissae-elicited forelimb placing test and a 12-point outcome scale. At 72 hours, brain blood volume, water content, blood–brain barrier (BBB) permeability, and protein expression of AQP-4 and MMP-9 were determined. Results: This collagenase model yielded well-defined striatal hematomas. Vibrissae-elicited forelimb placement was significantly (P<0·01) affected by ICH. However, there was no significant difference between the RIP and control groups at either 24 or 72 hours. A 12-point neurological deficit score also failed to differentiate between the RIP and control. There were no significant differences between the two groups in cerebral blood volumes, brain water content, Evans blue extravasations, and expressions of AQP-4 and MMP-9. Conclusions: Although RIP did not show a beneficial effect in our ICH model, treatment with RIP did not exacerbate ICH.

Acute ethanol treatment reduces blood–brain barrier dysfunction following ischemia/reperfusion injury

BACKGROUND AND PURPOSEnEthanol has been shown to provide neuroprotective effects, but the precise mechanisms by which these effects occur have yet to be investigated. In this study, we investigate blood-brain barrier (BBB) and edema level changes in association with expression of matrix metalloproteinases (MMP-2 and MMP-9) and aquaporins (AQP-4 and AQP-9) in ethanol treated rats following middle cerebral artery (MCA) occlusion.nnnMETHODSnAn ischemic stroke model was generated by occlusion of the right MCA for 2h in male Sprague-Dawley rats (n=72). Edema levels and BBB integrity following the ischemic event were studied by quantification of brain water content and extravasation of Evans blue following 24 and 48h of reperfusion, respectively. Expression of the proteins MMP-2 and MMP-9, as well as AQP-4 and AQP-9, were determined by Western blot analysis 3 and 24h after reperfusion.nnnRESULTSnTreatment with ethanol significantly reduced brain edema (P<0.01) and BBB dysfunction (P<0.05) when compared to the saline-treated control groups. The upregulation of MMP-2 and MMP-9, as well as AQP-4 and AQP-9, following ischemia/reperfusion, was significantly reduced in ethanol-treated groups (P<0.05).nnnCONCLUSIONSnEthanol ameliorates brain edema and BBB disruption after stroke, in association with a reduction in the expression of MMPs and AQPs. These results provide clues to ethanols neuroprotective properties.

Limb Ischemic Perconditioning Attenuates Blood-Brain Barrier Disruption by Inhibiting Activity of MMP-9 and Occludin Degradation after Focal Cerebral Ischemia.

Remote ischemic perconditioning (PerC) has been proved to have neuroprotective effects on cerebral ischemia, however, the effect of PerC on the BBB disruption and underlying mechanisms remains largely unknown. To address these issues, total 90 adult male Sprague Dawley (SD) rats were used. The rats underwent 90-min middle cerebral artery occlusion (MCAO), and the limb remote ischemic PerC was immediately applied after the onset of MCAO. We found that limb remote PerC protected BBB breakdown and brain edema, in parallel with reduced infarct volume and improved neurological deficits, after MCAO. Immunofluorescence studies revealed that MCAO resulted in disrupted continuity of claudin-5 staining in the cerebral endothelial cells with significant gap formation, which was significantly improved after PerC. Western blot analysis demonstrated that expression of tight junction (TJ) protein occludin was significantly increased, but other elements of TJ proteins, claudin-5 and ZO-1, in the BBB endothelial cells were not altered at 48 h after PerC, compared to MCAO group. The expression of matrix metalloproteinase (MMP-9), which was involved in TJ protein degradation, was decreased after PerC. Interestingly, phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2), an upstream of MMP-9 signaling, was significantly reduced in the PerC group. Our data suggest that PerC inhibits MMP-9-mediated occludin degradation, which could lead to decreased BBB disruption and brain edema after ischemic stroke.

Limb remote ischemic per-conditioning in combination with post-conditioning reduces brain damage and promotes neuroglobin expression in the rat brain after ischemic stroke

Abstract Purpose: Limb remote ischemic per-conditioning or post-conditioning has been shown to be neuroprotective after cerebral ischemic stroke. However, the effect of combining remote per-conditioning with post-conditioning on ischemic/reperfusion injury as well as the underlying mechanisms are largely unexplored. Methods: Here, adult male Sprague Dawley rats were subjected to middle cerebral artery occlusion (MCAO). The limb ischemic stimulus was immediately applied after onset of focal ischemia (per-conditioning), followed by repeated short episodes of remote ischemia 24 hr after reperfusion (post-conditioning). The infarct volume, motor function, and the expression of neuroglobin (Ngb) were measured at different durations after reperfusion. Results: We found that a single episode of limb remote per-conditioning afforded short-term protection, but combining repeated remote post-conditioning during the 14 days after reperfusion significantly ameliorated cerebral ischemia/reperfusion injury. Interestingly, we also found that ischemic per- and post-conditioning significantly increased expression of Ngb, an oxygen-binding globin protein that has been demonstrated to be neuroprotective against stroke, at peri-infarct regions from day 1 to day 14 following ischemia/reperfusion. Conclusion: Our results suggest that the conventional per-conditioning combined with post-conditioning may be used as a novel neuroprotective strategy against ischemia-reperfusion injury, and Ngb seems to be one of the important players in limb remote ischemia-mediated neuroprotection.

Preconditioning in neuroprotection: From hypoxia to ischemia

Sublethal hypoxic or ischemic events can improve the tolerance of tissues, organs, and even organisms from subsequent lethal injury caused by hypoxia or ischemia. This phenomenon has been termed hypoxic or ischemic preconditioning (HPC or IPC) and is well established in the heart and the brain. This review aims to discuss HPC and IPC with respect to their historical development and advancements in our understanding of the neurochemical basis for their neuroprotective role. Through decades of collaborative research and studies of HPC and IPC in other organ systems, our understanding of HPC and IPC-induced neuroprotection has expanded to include: early- (phosphorylation targets, transporter regulation, interfering RNA) and late- (regulation of genes like EPO, VEGF, and iNOS) phase changes, regulators of programmed cell death, members of metabolic pathways, receptor modulators, and many other novel targets. The rapid acceleration in our understanding of HPC and IPC will help facilitate transition into the clinical setting.

Assessment of Serum UCH-L1 and GFAP in Acute Stroke Patients

A rapid and reliable diagnostic test to distinguish ischemic from hemorrhagic stroke in patients presenting with stroke-like symptoms is essential to optimize management and triage for thrombolytic therapy. The present study measured serum concentrations of ubiquitin C-terminal hydrolase (UCH-L1) and glial fibrillary astrocytic protein (GFAP) in acute stroke patients and healthy controls and investigated their relation to stroke severity and patient characteristics. We also assessed the diagnostic performance of these markers for the differentiation of intracerebral hemorrhage (ICH) from ischemic stroke (IS). Both UCH-L1 and GFAP concentrations were significantly greater in ICH patients than in controls (pu2009<u20090.0001). However, exclusively GFAP differed in ICH compared with IS (pu2009<u20090.0001). GFAP yielded an AUC of 0.86 for differentiating between ICH and IS within 4.5hrs of symptom onset with a sensitivity of 61% and a specificity of 96% using a cut-off of 0.34ng/ml. Higher GFAP levels were associated with stroke severity and history of prior stroke. Our results demonstrate that blood UCH-L1 and GFAP are increased early after stroke and distinct biomarker-specific release profiles are associated with stroke characteristics and type. We also confirmed the potential of GFAP as a tool for early rule-in of ICH, while UCH-L1 was not clinically useful.

Safety and Feasibility of Remote Limb Ischemic Preconditioning in Patients With Unilateral Middle Cerebral Artery Stenosis and Healthy Volunteers.

Previous studies have indicated a neuroprotective effect of remote limb ischemic preconditioning. The aim of the present study was to assess whether upper arm ischemic preconditioning is feasible and safe in patients with unilateral middle cerebral artery (MCA) stenosis compared to healthy volunteers. Ten patients with unilateral MCA stenosis and 24 healthy volunteers underwent limb ischemic preconditioning, consisting of five cycles of 5-min inflations of a blood pressure cuff to 200 mmHg around an upper limb followed by 5 min of reperfusion. Limb ischemic preconditioning has no significant effect on the heart rate, oxygenation index, or mean flow velocity in patients with unilateral MCA stenosis or healthy volunteers. However, healthy volunteers showed a reduction in blood pressure 30 min following reperfusion of the last cycle. Limb ischemic preconditioning was found to be safe and well tolerated in both patients and healthy volunteers. We highlight the potential of limb ischemic preconditioning as an adjunct to neuroprotective treatment.

Herbal Formula Danggui-Shaoyao-San Promotes Neurogenesis and Angiogenesis in Rat Following Middle Cerebral Artery Occlusion

Current studies demonstrated that traditional Chinese herbal formula Danggui-Shaoyao-San (DSS) is not only used for the treatment of menstrual disorder, but has also found its use in neurological diseases. However, the neuroprotective role of DSS on ischemia-induced brain injury is still unclear. The aim of the present study is to explore the effect of DSS in ischemic brain injury. Total 30 adult female Sprague-Dawley rats underwent 90 min transient middle cerebral artery occlusion (MCAO). DSS (600 mg/kg) was administered through the intragastric route at the time of reperfusion and then performed every day thereafter until sacrifice. Results showed that DSS treatment significantly improved neurobehavioral outcomes (N=10 per group, P<0.05). Immunohistochemical staining showed that microvessel density in the perifocal region of DSS-treated rats was significantly increased compared to the saline-treated group (N=4 per group, P<0.01). Similarly, the numbers of BrdU(+)/DCX(+) cells in the subventricular zone were increased in DSS-treated rats compared to the saline-treated group (P<0.05). Furthermore, we demonstrated that DSS treatment activated vascular endothelial growth factor (N=4 per group, P<0.05) and promoted eNOS phosphorylation (N=4 per group, P<0.05). Thus, we concluded that DSS promoted focal angiogenesis and neurogenesis, and attenuated ischemia-induced brain injury in rats after MCAO, suggesting that DSS is a potential drug for ischemic stroke therapy.

Different expression of ubiquitin C-terminal hydrolase-L1 and αII-spectrin in ischemic and hemorrhagic stroke: Potential biomarkers in diagnosis.

The two primary categories of stroke, ischemic and hemorrhagic, both have fundamentally different mechanisms and thus different treatment options. These two stroke categories were applied to rat models to identify potential biomarkers that can distinguish between them. Ischemic stroke was induced by middle cerebral artery occlusion (MCAO) without reperfusion while hemorrhagic stroke was induced by injecting collagenase IV into the striatum. Brain hemispheres and biofluids were collected at two time points: 3 and 6h after stroke. Known molecules were tested on the rat samples via quantitative immunoblotting (injured brain, CSF) and Banyans proprietary ELISA assays (CSF, serum). The injured brain quantitative analyses revealed that αII-spectrin breakdown products (SBDP150, SBDP145) were strongly increased after 6h ischemia. In CSF, SBDP145 and ubiquitin C-terminal hydrolase-L1 (UCH-L1) levels were elevated after 6h ischemic stroke detected by Western blot and ELISA. In serum UCH-L1 levels were increased after 3 and 6h of ischemia detected by ELISA. However, levels of those proteins in hemorrhagic stroke remain normal. In summary, in both the brain and the biofluids, SBDPs and UCH-L1 were elevated after ischemic but not hemorrhagic stroke. These molecules behaved differently in the two stroke models and thus may be capable of being differentiated.