Left Middle Cerebral Artery Occlusion Research Articles

Characteristics of Cerebral Ischemia in Major Rat Stroke Models of Middle Cerebral Artery Ligation through Craniectomy

The refinement of experimental stroke models is important for further development of neuroprotective interventions. Our goal was to study the reproducibility of outcomes obtained in five rat models of middle cerebral artery (MCA) ligation in order to identify the optimal model for the preclinical studies. In Part 1 of the experiments, systolic blood flow velocity (sBFV) and cerebral area at risk (AR) were determined immediately after the onset of brain ischemia induced in different ways in Wistar rats. After that, another set of experiments was performed (Part 2 of the experiments), now aimed at the assessment of the delayed outcome of five different models of cerebral ischemia designated as Versions 1-5. The versions were: Version 1 - 40-minute left MCA (LMCA) occlusion with reperfusion; Version 2 - permanent LMCA ligation; Version 3 - permanent ligation of both LMCA and left common carotid artery (CCA); Version 4 - permanent LMCA and bilateral CCA (bCCA) ligation; Version 5 - permanent LMCA ligation and 40-minute bCCA occlusion. The infarct size (IS) was quantified using triphenyltetrazolium chloride staining. The severity of neurological deficit was assessed by the Garcia score. The extent of brain edema was determined by calculating the difference in volumes of affected and contralateral hemispheres. Within a relatively big AR, Versions 1 and 2 resulted in a small IS [0·2 (0·0; 0·4)% and 0·3 (0·0; 0·7)%, respectively, P > 0·05]. Unlike that and comparable with AR, Version 3 resulted in a greater, albeit more variable IS [5·9 (2·1; 8·3)%, P < 0·0001 vs. Version 2]. Also comparable with AR, Versions 4 and 5 produced greatest values of IS [14·5 (11·4; 17·9)% and 11·3 (10·1; 14·2)%, respectively]; this parameter was most reproducible in Version 5. A significant decrease in neurological deficit score was found in Versions 4 and 5. Again, the reproducibility of the data on neurological outcome was higher in Version 5 versus Version 4. Comparative analysis of several Versions of focal cerebral ischemia within a single study might be helpful in better understanding of the mechanisms underlying the development and aftermath of stroke. Permanent LMCA ligation plus transient bilateral CCA occlusion produced most consistent results and might be recommended for preclinical studies.

Over-expression of VEGF in marrow stromal cells promotes angiogenesis in rats with cerebral infarction via the synergistic effects of VEGF and Ang-2

bThis study explored whether the transplantation of modified marrow stromal cells (MSCs) has angiogenic effects in a left middle cerebral artery occlusion infarction/reperfusion (MCAO I/R) rat model and preliminarily examined the mechanism of angiogenesis following cerebral infarction. MSCs were isolated by using a direct adherent method and cultured. Vascular endothelial growth factor (VEGF) was transfected into MSCs by employing the liposome transfection. The transfection efficiency was measured by the optical density method. The protein expression of VEGF gene before and after transfection was measured by Western blotting. SD rat model of transient occlusion of the left middle cerebral artery was established by using an approach of intra-luminal occlusion. Tetrazolium (TTC) and HE staining were performed to observe the cerebral infarction. ELISAs were used to measure the levels of VEGF in the rat cerebral tissues. The expression patterns of angiopoietin-2 (Ang-2) and CD34 in cells surrounding the area of infarction were immunohistochemistrically observed. Ang-2 protein expression in the tissue surrounding the area of infarction was measured by Western blotting. VEGF expression in the MSCs increased after transfection at a rate of approximately 28%±3.4%. ELISA showed that the expression of VEGF in the cerebral tissue was significantly increased after induction of infarction, peaking on the 4th day and decreasing to the levels of the sham surgery group (normal) within 7 to 10 days. The VEGF level was significantly higher at each time point in the VEGF-MSC and MSC groups compared to the model group. Moreover, the VEGF level was higher in the VEGF-MSC group than in the MSC group and stayed relatively high until the 10th day. The immunohistochemical results showed that 10 days after the infarction, the number of Ang-2 and CD34-expressing cells in the area surrounding the infarction was significantly higher in the VEGF-MSC group and the MSC group compared to the model group. Moreover, the VEGF level was higher in the VEGF-MSC group than the MSC group. A similar trend in Ang-2 protein expression was revealed by Western blotting. In the MCAO rat model transfected with modified MSCs over-expressing VEGF, compared to the MSC transplantation group, the concentration of VEGF was significantly increased in the brain tissue after cerebral infarction. In addition, the level of Ang-2 was up-regulated, with angiogenesis promoted, the blood supply to the areas surrounding the cerebral infarction increased, and neurological function improved. We are led to speculate that the synergistic effects of VEGF and Ang-2 may be responsible for the angiogenesis following cerebral infarction.

Neuronal apoptosis and synaptic density in the dentate gyrus of ischemic rats' response to chronic mild stress and the effects of Notch signaling.

Our previous research highlighted an inconsistency with Notch1 signaling-related compensatory neurogenesis after chronic mild stress (CMS) in rodents suffering from cerebral ischemia, which continue to display post-stroke depressive symptoms. Here, we hypothesize that CMS aggrandized ischemia-related apoptosis injury and worsened synaptic integrity via gamma secretase-meditated Notch1 signaling. Adult rats were exposed to a CMS paradigm after left middle cerebral artery occlusion (MCAO). Open-field and sucrose consumption testing were employed to assess depression-like behavior. Gene expression of pro-apoptotic Bax, anti-apoptotic Bcl-2, and synaptic density-related synaptophysin were measured by western blotting and real-time PCR on Day 28 after MCAO surgery. CMS induced depressive behaviors in ischemic rats, which was accompanied by an elevation in Bax/bcl-2 ratio, TUNEL staining in neurons and reduced synaptophysin expression in the dentate gyrus. These collective effects were reversed by the gamma-secretase inhibitor DAPT (N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-phenyl-glycine t-butyl ester). We found that post-stroke stressors made neurons in the dentate gyrus vulnerable to apoptosis, which supports a putative role for Notch signaling in neural integrity, potentially in newborn cells’ synaptic deficit with regard to preexisting cells. These findings suggest that post-stroke depression therapeutically benefits from blocking gamma secretase mediated Notch signaling, and whether this signaling pathway could be a therapeutic target needs to be further investigated.

Effect of Semax and its C-terminal Fragment Pro-Gly-Pro on the Expression of VEGF Family Genes and their Receptors in Experimental Focal Ischemia of the Rat Brain

The synthetic peptide Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is used successfully in acute stroke therapy. In spite of numerous studies on the subject, many aspects of the neuroprotective effects of the peptide remain unknown. We studied the action of Semax and its C-terminal tripeptide Pro-Gly-Pro on the expression of the VEGF gene family (Vegf-a, Vegf-b, Vegf-c, Vegf-d, and Plgf) and their receptors (Vegfr-1, Vegfr-2, and Vegfr-3) in the frontoparietal cortex region of the rat brain at 3, 24, and 72 h after permanent left middle cerebral artery occlusion (pMCAO). The relative mRNA level of the genes studied was assessed using real-time reverse transcription-PCR. The Vegf-b and Vegf-d genes were most affected by the peptides, which resulted in their most noticeable activation at 3 h after pMCAO. The level of Vegf-d transcripts decreased considerably, whereas the mRNA level of the Vegf-b gene was significantly increased after 72 h of treatment with each of the peptides. In addition, the effects of the peptides on the expression of the Vegf-b and Vegf-d genes were the opposite of the action of ischemia. It is suggested that the identified effects of the peptides diminish the effects of ischemia, thus participating in the positive therapeutic effect of Semax on ischemic stroke.

Ischemic Preconditioning Attenuates Brain Edema After Experimental Intracerebral Hemorrhage

Ischemic preconditioning (IPC) provides protection against subsequent severe ischemic injury. A recent study found that cerebral IPC prolongs bleeding time. In this study, we examined whether IPC protects against intra-cerebral hemorrhage (ICH)-induced brain edema formation and whether IPC affects blood coagulation. There were three sets of experiments in this study. In the first set, male Sprague-Dawley rats were preconditioned with either 15 min of left middle cerebral artery occlusion, an IPC stimulus, or a sham operation. Three days later, rats received an infusion of autologous whole blood in the ipsilateral or contralateral caudate. Rats were killed 24 h later for brain water content measurement. In the second set, rats underwent 15 min of IPC or a sham operation. Three days later, rats were used for bleeding and thrombin clotting time tests. In the third set, the levels of p44/42 mitogen-activated protein kinases (MAPKs), heme oxygenase-1 (HO-1), transferrin (Tf), and transferrin receptor (TfR) in the brain 24 or 72 h after IPC were examined. We found that IPC reduced ICH-induced brain edema when blood was injected into the ipsilateral caudate but it did not when blood was injected into the contralateral caudate. IPC resulted in prolongation of bleeding time and thrombin clotting time. IPC also induced the activation of p44/42 MAPKs and upregulation of HO-1, Tf, and TfR levels in the ipsilateral caudate. These results suggest that IPC protects against ICH-induced brain edema formation and decreases blood coagulation. The protection of IPC against ICH is mainly due to local factors in the brain and may be related to activation of p44/42 MAPKs and upregulation of HO-1, Tf, and TfR.

Effects of medullary administration of nitric oxide precursor on cardiovascular responses and neurotransmission during static exercise in stroke rats

Rats with a 90‐min left middle cerebral artery occlusion followed by 24‐hour reperfusion (MCAO), pressor responses during muscle contractions were attenuated, as were glutamate in the left rostral ventrolateral medulla (RVLM) and left caudal VLM (CVLM), but GABA increased in left RVLM and CVLM (Brain Res. 2002: 952). This study determined the effects of L‐arginine (L‐Arg), a nitric oxide (NO) precursor, within the RVLM or CVLM on cardiovascular activity and glutamate/GABA levels during static exercise in left‐sided MCAO rats. Microdialysis of L‐Arg into the left RVLM further attenuated pressor and heart rate (HR) responses, decreased glutamate and increased GABA levels during muscle contractions. Administration of N(G)‐monomethyl‐L‐arginine, an NO‐synthase inhibitor, reversed the effects. In contrast, L‐Arg administration into left CVLM potentiated pressor and HR responses, increased glutamate and decreased GABA levels during muscle contractions. However, simultaneous L‐Arg microdialysis into left RVLM and CVLM elicited responses similar to those following its infusion into RVLM. Results suggest that NO within the RVLM and CVLM plays an important role in modulating cardiovascular responses and glutamate/GABA neurotransmission during static exercise following stroke, and that the RVLM‐NO mechanism has a dominant effect in medullary regulation of cardiovascular function.

Effects of exercise training on synaptic plasticity in rats with focal cerebral infarction

To examine the roles of exercise training in the improvement of damaged neural function and synaptic plasticity. An infarction model was induced by left middle cerebral artery occlusion (MCAO). A total of 70 adult Sprague-Dawley rats were randomly divided into 3 groups: physical exercise group (n = 30) undergoing running wheel exercise daily after MCAO, control group (n = 30) and sham-operated group (n = 10). The latter two groups were fed in standard cages without any special training exercise. The rats were scarified at Days 3, 7, 14, 21 and 35 for the evaluation of neural function by neurological severity scores (NSS). And the synaptic ultrastructures at peri-infarction region were examined by specific marker synaptophysin (SYN). Synaptic ultrastructures at peri-infarction region were observed in both the control and exercise training groups. The presynaptic and postsynaptic membranes were relatively intact. And the presynaptic membranes had more synaptic vesicles from Day 7 post-ischemia. The number of SYN positive cells significantly increased in the exercise training group (21 d: 0.8 ± 0.1; 35 d: 0.7 ± 0.1) versus those in the control group (21 d: 0.4 ± 0.1; 35 d: 0.5 ± 0.1) at Days 21 and 35 post-ischemia (P < 0.05). Moreover, the neurological severity scores in the exercise training group (7 d: 7.8 ± 0.8; 14 d: 5.6 ± 0.8; 21 d: 3.3 ± 0.8; 35 d: 3.0 ± 0.8) showed a quicker declination versus those in the control group (7 d: 8.8 ± 0.7; 14 d: 7.7 ± 0.9; 21 d: 6.9 ± 0.8; 35 d: 4.2 ± 0.8) from Day 7 post-ischemia (P < 0.05). Exercise training plays an important role in the recovery of damaged neural function and synaptic plasticity after cerebral infarction in rats.

Overexpression of CXCR4 in mesenchymal stem cells promotes migration, neuroprotection and angiogenesis in a rat model of stroke

BackgroundStromal cell-derived factor-1 (SDF-1) and its cognate receptor, chemokine (C-X-C motif) receptor 4 (CXCR4), are involved in the migration of stem cells. AimTo test the hypothesis that mesenchymal stem cells (MSCs) with genetically modified CXCR4 can promote their own recruitment around the ischemic core. MethodsLentiviral vectors were used to overexpress the CXCR4-eGFP fusion protein (CXCR4/eGFP) or eGFP only (eGFP) or to introduce siRNA targeting endogenous CXCR4 (siRNA/eGFP) in rat mesenchymal stem cells (rMSCs). Rats were injected with either the transduced rMSCs or PBS as a control via the femoral vein following a left middle cerebral artery occlusion (MCAO). ResultsOne week after MCAO, immunofluorescence staining revealed a significant increase in the number of eGFP-positive cells surrounding the infarct areas in the CXCR4-rMSC-treated group compared to the rMSC-treated control group. Conversely, there was a significant reduction in the number of eGFP-positive cells in the siRNA-rMSC-treated group. Moreover, there was an increase in the capillary vascular volume of the peri-infarct area, a reduction in the volume of the cerebral infarction and improved neurological function in the CXCR4-rMSC-treated group compared to those in the rMSC-, siRNA-rMSC- or PBS-treated groups. ConclusionCXCR4 overexpression in the rMSCs promoted their mobilization and enhanced neuroprotection in a rat cerebral ischemia model. This strategy may be a useful therapeutic approach for treating ischemic stroke.

Moyamoya Syndrome Associated With Gamma Knife Surgery for Cerebral Arteriovenous Malformation

A 30-year-old female developed moyamoya syndrome after gamma knife surgery (GKS) for cerebral arteriovenous malformation (AVM), and was treated with bypass surgery. She suffered from flittering scotoma, right transient hemianopsia, and headache for 1 year. Cerebral angiography revealed a Spetzler-Martin grade III AVM located in the left occipital lobe. After staged embolization, GKS was performed with a minimum dose of 20 Gy to the periphery of the nidus at the 50% isodose level of the maximum target dose. Gradual nidus regression was achieved, and the clinical symptoms disappeared completely. However, at 30 months after GKS, the patient suffered transient ischemic attack. Cerebral angiography showed left middle cerebral artery occlusion with moyamoya vessels. The patient underwent direct and indirect bypass surgery. After surgery, the patient was free from ischemic symptoms. Chronic inflammation and long-term changes in expression of cytokines and growth factors after GKS may have triggered this case.

Proteomic Analysis of Rat Plasma Following Transient Focal Cerebral Ischemia

This study aimed to identify plasma protein changes in a rat model of ischemic stroke using a proteomic approach. Four male Sprague-Dawley rats (3-6 months old) were subjected to 90 min of left middle cerebral artery occlusion under anesthesia with 1.5% isoflurane in O(2)/air followed by 24-h reperfusion. Blood samples (~100 µl) were collected at baseline, at the end of 90-min middle cerebral artery occlusion and at 24-h postreperfusion. Brain injuries were assessed by MRI at 24-h postreperfusion. Quantitative comparison of global plasma protein expression was performed using 2D differential in-gel electrophoresis. Differentially expressed protein spots were identified using peptide sequencing tandem mass spectrometry. These rats had clear brain infarction in the left hemisphere detected by MRI. Thirty-three protein spots of plasma samples were differentially expressed following focal cerebral ischemia/reperfusion. These protein spots belonged to eight proteins. Six of them (α2-macroglobulin, complement C3, inter-α- trypsin inhibitor heavy chain H3, serum albumin, haptoglobin and transthyretin), which are a class of acute-phase proteins, changed significantly. This study describes the responses of young rats to focal cerebral ischemia and suggests that future studies should use aged animals to better mimic the clinical ischemic stroke setting.

Intracranial transplantation of monocyte‐derived multipotential cells enhances recovery after ischemic stroke in rats

Cell transplantation has emerged as a potential therapy to reduce the neurological deficits caused by ischemic stroke. We previously reported a primitive cell population, monocyte-derived multipotential cells (MOMCs), which can differentiate into mesenchymal, neuronal, and endothelial lineages. In this study, MOMCs and macrophages were prepared from rat peripheral blood and transplanted intracranially into the ischemic core of syngeneic rats that had undergone a left middle cerebral artery occlusion procedure. Neurological deficits, as evaluated by the corner test, were less severe in the MOMC-transplanted rats than in macrophage-transplanted or mock-treated rats. Histological evaluations revealed that the number of microvessels that had formed in the ischemic boundary area by 4 weeks after transplantation was significantly greater in the MOMC-transplanted rats than in the control groups. The blood vessel formation was preceded by the appearance of round CD31(+) cells, which we confirmed were derived from the transplanted MOMCs. Small numbers of bloodvessels incorporating MOMC-derived endothelial cells expressing a mature endothelial marker RECA-1 were detected at 4 weeks after transplantation. In addition, MOMCs expressed a series of angiogenic factors, including vascular endothelial growth factor, angiopoetin-1, and placenta growth factor (PlGF). These findings provide evidence that the intracranial delivery of MOMCs enhances functional recovery by promoting neovascularization in a rat model for ischemic stroke.

Anterior Communicating Artery Aneurysm Rupture After Intravenous Thrombolysis for Acute Middle Cerebral Artery Thromboembolism

The use of intravenous recombinant tissue plasminogen activator (IV rtPA) has become an integral part of modern acute ischemic stroke management; however, its use has been associated with the development of intracranial hemorrhage in 6.4% of patients. It is possible that underlying and unsuspected vascular lesions, such as cerebral aneurysms, may lead to intracranial hemorrhage after IV rtPA thrombolysis. We present a previously unreported case of a 51-year-old woman who presented with subarachnoid hemorrhage from an acutely ruptured anterior communicating artery aneurysm after IV rtPA treatment for acute left middle cerebral artery thromboembolism. The patient underwent mechanical thromboembolectomy of the left middle cerebral artery occlusion with resultant TIMI (Thrombolysis In Myocardial Infarction) grade I recanalization, followed by coil embolization of the anterior communicating artery aneurysm. The patient never improved neurologically, and she ultimately died. Screening to identify patients at risk for development of hemorrhagic complications from underlying structural vascular lesions before the use of IV rtPA with computed tomography angiography should be considered.

Calcitonin gene-related peptide prevents blood–brain barrier injury and brain edema induced by focal cerebral ischemia reperfusion

Cerebral ischemia is one of the diseases that most compromise the human species. Therapeutic recovery of blood–brain barrier (BBB) disruption represents a novel promising approach to reduce brain injury after stroke. To determine the effects of calcitonin gene-related peptide (CGRP) on the BBB participate in stroke progression, rat cerebral ischemia reperfusion injury was induced by a 2-hour left transient middle cerebral artery occlusion (MCAO) using an intraluminal filament, followed by 46h of reperfusion. CGRP (1μg/ml) at the dose of 3μg/kg (i.p.) was administered at the beginning of reperfusion. Subsequently, 48h after MCAO, arterial blood pressure, infarct volume, water content, BBB permeability, BBB ultrastructure, levels of aquaporin-4 (AQP4) and its mRNA were evaluated. CGRP could reduce arterial blood pressure (P<0.001), infarct volume (P<0.05), cerebral edema (P<0.01), BBB permeability (P<0.05), AQP4 mRNA expression (P<0.05) and AQP4 protein expression (P<0.01). Furthermore, CGRP treatment improved ultrastructural damage of capillary endothelium cells and decreased the loss of the tight junction observed by transmission electronic microscopy (TEM) after 46h of reperfusion. Our findings show that CGRP significantly reduced postischemic increase of brain edema with a 2-hour therapeutic window in the transient model of focal cerebral ischemia. Moreover, it seems that at least part of the anti-edematous effects of CGRP is due to decrease of BBB disruption by improving ultrastructural damage of capillary endothelium cells, enhancing basal membrane, and inhibiting AQP4 and its mRNA over-expression. The data of the present study provide a new possible approach for acute stroke therapy by administration of CGRP.

Aggressive intervention to treat a young woman with intracranial hemorrhage following unsuccessful intravenous thrombolysis for left middle cerebral artery occlusion

Stroke patients whose condition does not improve after intravenous administration of tissue plasminogen activator (tPA) may be candidates for endovascular intervention. Patients with new intracerebral hemorrhage noted during such interventions pose a difficult challenge to neurointerventionists and are often sequestered as treatment failures and deemed inappropriate for intraarterial recanalization efforts. The authors present a case in which aggressive intervention was performed despite evidence of contrast extravasation on preintervention angiography. This 37-year-old woman presented with an occlusion of the M(1) segment of the left middle cerebral artery and a National Institutes of Health Stroke Scale score of 24. She received intravenous tPA without improvement. Angiography revealed M(1) thrombus as well as active contrast extravasation without arterial displacement. Thromboaspiration was performed in light of her known hemorrhage with excellent recanalization. Immediate postprocedure imaging demonstrated a large insular hematoma and emergent craniectomy and hematoma evacuation were performed. At 4 months' follow-up, the patient was living at home, was ambulating, and had excellent comprehension with mild expressive aphasia. There is little peer-reviewed data in the literature to aid in the decision-making process when contrast extravasation is recognized at the time of preinterevention angiography. Continuation of mechanical endovascular stroke intervention, in light of active contrast extravasation, may be warranted in young patients with major deficits and absence of arterial displacement or delayed global filling. Further thrombolytics are not advised. In select stroke patients, continuation of a planned attempt at mechanical recanalization without the further use of thrombolytics may be warranted in light of known intracerebral hemorrhage.

In Vivo Real-Time Multiphoton Imaging of T Lymphocytes in the Mouse Brain After Experimental Stroke

To gain a better understanding of T cell behavior after stroke, we have developed real-time in vivo brain imaging of T cells by multiphoton microscopy after middle cerebral artery occlusion. Adult male hCD2-GFP transgenic mice that exhibit green fluorescent protein-labeled T cells underwent permanent left distal middle cerebral artery occlusion by electrocoagulation (n=6) or sham surgery (n=6) and then multiphoton laser imaging 72 hours later. Extravasated T cell number significantly increased after middle cerebral artery occlusion versus sham. Two T cell populations existed after middle cerebral artery occlusion, possibly driven by 2 T cell subpopulations; 1 had significantly lower and the other significantly higher track velocity and displacement rate than sham. The different motilities and behaviors of T cells observed using our imaging approach after stroke could reveal important mechanisms of immune surveillance for future therapeutic exploitations.

Aβ and Aδ but not C-fibres are involved in stroke related pain and allodynia: an experimental study in mice

Cerebral ischaemia is a leading cause of death and disability, including severe complications such as memory disturbance, palsy, and spasticity. Central post-stroke pain (CPSP) is a complication of cerebral ischaemia, and is characterized clinically by spontaneous pain and attacks of allodynia and dysaesthesia. However, the detailed mechanisms of CPSP are not well established. Herein, we have examined alterations of the current stimulus threshold of primary afferent neurons or the nociceptive threshold against mechanical stimuli in mice receiving left middle cerebral artery occlusion (MCAO). Alterations of current stimulus threshold and the development of mechanical allodynia in hind paws were measured after MCAO using a Neurometer and the von Frey filament test, respectively. Development of cerebral infarction was clearly observed on day 1 and day 3 after MCAO. For the estimation of current stimulus threshold measured by the Neurometer, the sensitivity of Aδ and Aβ fibres (at 2000 and 250 Hz stimulation, respectively) was significantly increased on day 3 after MCAO, while that of C fibres (at 5 Hz stimulation) was unaltered. In addition, the paw withdrawal threshold of the left hind paw as measured by the von Frey filament test was significantly decreased on day 1 and day 3 after MCAO when compared with day 0, while that in the right hind paw was not different. The data suggested the development of bilateral hyperaesthesia in this model. Further, mechanical allodynia developed in the ipsilateral side to the MCAO. Potentially, myelinated A fibre-specific hypersensitization after stroke may have contributed to these symptoms.

Multiparametric assessment of acute and subacute ischemic neuronal damage: A small animal positron emission tomography study with rat photochemically induced thrombosis model

We evaluated sequential changes in rat brain function up to 14 days after focal ischemic insult with a small animal positron emission tomography (PET). Unilateral focal ischemic cerebral damage was induced by left middle cerebral artery occlusion with a photochemically induced thrombosis (PIT) method. PET scans were conducted with [(11)C](R)-PK11195 ([(11)C](R)-PK) for peripheral benzodiazepine receptor (PBR), [(11)C]flumazenil ([(11)C]FMZ) for central benzodiazepine receptor (CBR), and [(18)F]fluoro-2-deoxy-D-glucose ([(18)F]FDG) for glucose metabolism at before (as "Normal") and after PIT. At 1 and 3 days after PIT, [(18)F]FDG indicated lower uptake in the infarct area. Interestingly, unexpectedly high-[(18)F]FDG uptake was observed in the peri-infarct area surrounding the infarct area at day 7. The high-[(18)F]FDG uptake region completely overlapped with the high-[(11)C](R)-PK uptake region at day 7, which resulted in the underestimation of neuronal damage. Immunohistochemical data also suggested that the high-[(18)F]FDG uptake peak at day 7 was caused by inflammation including microglial cell activation. In contrast, imaging with [(11)C]FMZ indicated cortical neuronal damage on days 7 and 14 without any disturbance by microglial formation. These results indicated that [(18)F]FDG might not be a suitable ligand for ischemic neuronal damage detection from acute to subacute phases.

Thrombopoietin Protects the Brain and Improves Sensorimotor Functions: Reduction of Stroke-Induced MMP-9 Upregulation and Blood—Brain Barrier Injury

This study was conducted to determine the protective efficacy and mechanisms of thrombopoietin (TPO) intervention in experimental focal stroke. Male rats underwent 2 hours of left middle cerebral artery occlusion (MCAO) followed by 22 hours of reperfusion. Vehicle or TPO (0.03 to 1.00 μg/kg) was administered intravenously immediately after reperfusion. Brain infarct and swelling, neurologic deficits, matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), TPO and c-Mpl (TPO receptor) mRNA, MMP-9 enzyme activity and protein expression, and the integrity of the blood-brain barrier (BBB) were subsequently measured. MCAO reperfusion produced a large infarct and swelling after stroke. Thrombopoietin significantly reduced these in a dose-dependent manner. The most effective TPO dose, 0.1 μg/kg, when administrated immediately or 2 hours after reperfusion, significantly reduced infarct and swelling and ameliorated neurologic deficits after stroke. Stroke-induced increases in cortical MMP-9 mRNA, enzyme activity and protein expression, TIMP-1 mRNA, and Evans blue extravasation were reduced by TPO intervention. Thrombopoietin did not alter cortical TPO or c-Mpl mRNA expression, blood pressure, heart rate, blood hematocrit, or platelets. This is the first demonstration of TPO's efficacy in reducing ischemic brain injury and improving functional outcome, partly by inhibiting the stroke-induced increase in MMP-9 and the early, negative effects on the BBB.

The effects of early exercise on brain damage and recovery after focal cerebral infarction in rats

AimExercise can be used to enhance neuroplasticity and facilitate motor recovery after a stroke in rats. We investigated whether treadmill running could reduce brain damage and enhance the expression of midkine (MK) and nerve growth factor (NGF), increase angiogenesis and decrease the expression of caspase-3.MethodsSeventy-seven Wistar rats were split into three experimental groups (ischaemia-control: 36, ischaemia-exercise: 36, sham-exercise: 5). Stroke was induced by 90-min left middle cerebral artery occlusion using an intraluminal filament. Beginning on the following day, the rats were made to run on a treadmill for 20 min once a day for a maximum of 28 consecutive days. Functional recovery after ischaemia was assessed using the beam-walking test and a neurological evaluation scale in all rats. Infarct volume, and the expression of MK, NGF, anti-platelet-endothelial cell adhesion molecule (PECAM-1), and caspase-3 were evaluated at 1, 3, 5, 7, 14 and 28 days after the induction of ischaemia.ResultsOver time motor coordination and neurological deficits improved more in the exercised group than in the non-exercised group. The infarct volume in the exercised group (12.4 ± 0.8%) subjected to treadmill running for 28 days was significantly decreased compared with that in the control group (19.8 ± 4.2%, P < 0.01). The cellular expression levels of MK, NGF and PECAM-1 were significantly increased while that of caspase-3 was decreased in the peri-infarct area of the exercised rats.ConclusionsOur findings show that treadmill exercise improves motor behaviour and reduces neurological deficits and infarct volume, suggesting that it may aid recovery from central nervous system injury.

The effects of citicoline combined with rehabilitative training on neural plasticity after focal cerebral ischemia

Objective To investigate the effects of citicoline combined with rehabilitative training on motor function after focal cerebral ischemia. Methods One hundred and twenty male adult Sprague-Dawley rats ( 3 months old) were subjected to left middle cerebral artery occlusion (MCAO) by suturing. Ninety-six of them were randomly divided into four groups of 24: a control group, a drug group, a rehabilitative training group, and a drug combined with rehabilitative training group. The rats in the control group did not receive any treatment. Three days after reperfusion, those in the drug group received 500 mg/kg of citicoline daily; those in the rehabilitative training group received motor training including balancing, grasping, rotating and walking exercises; those in the combined group received both citicoline and the motor training program. Behavioral tests were administered at the 7th, 14th and 21st days after MCAO. At the same time points, immunohistochemistry was used to detect calcium-binding protein S100 and β-tubulin expression in the peri-ischemia region of the cortex. Results ①As compared with the control group, the drug group at the 7th, 14th and 21st day after MCAO and the other two groups at the 7th day after MCAO showed no significant difference in average behavior scores. But at the 14th and 21st day the rehabilitative training group as well as the drug combined with rehabilitative training group had average behavior scores significantly superior to those of the control group, especially in the drug combined with rehabilitative training group. ②As compared with the control group, the expression of S100 and β-tubulin in the drug and rehabilitative training groups at the 7th day after MCAO showed no significant difference. In the drug combined with rehabilitative training group the average score was significantly higher than in the other groups at the 7th day after MCAO. All the other groups had average scores significantly higher than that of the controls at the 14th and 21st day after MCAO, especially the drug combined with rehabilitative training group. Conclusions Citicoline combined with rehabilitative training can significantly improve motor function recovery in rats. The effect of the combined modalities was more obvious, and the functional enhancement might be partially attributable to the up-regulation of S100 and β-tubulin in the cortex. Key words: Cerebral ischemia; Citicoline; Rehabilitative training; Calcium-binding protein; β-tubulin