Neuroprotective effects of meloxicam on transient brain ischemia in rats:the two faces of anti-inflammatory treatments

The inflammato ry response plays an important role in neuroprotection and regeneration after ischemic insult.The use of non-ste roidal anti-inflammatory drugs has been a matter of debate as to whether they have beneficial or detrimental effects.In this context,the effects of the anti-inflammatory agent meloxicam have been scarcely documented after stro ke,but its ability to inhibit both cyclooxygenase isoforms(1 and 2) could be a promising strategy to modulate postischemic inflammation.This study analyzed the effect of meloxicam in a transient focal cerebral ischemia model in rats,measuring its neuroprotective effect after 48 hours and 7 days of reperfusion and the effects of the treatment on the glial scar and regenerative events such as the generation of new progenitors in the subventricular zone and axonal sprouting at the edge of the damaged area.We show that meloxicam’s neuroprotective effects remained after 7 days of reperfusion even if its administration was restricted to the two first days after ischemia.Moreover,meloxicam treatment modulated glial scar reactivity,which matched with an increase in axonal sprouting.However,this treatment decreased the formation of neuronal progenitor cells.This study discusses the dual role of anti-inflammatory treatments after stro ke and encourages the careful analysis of both the neuroprotective and the regenerative effects in preclinical studies.

Selective ischemic-hemisphere targeting Ginkgolide B liposomes with improved solubility and therapeutic efficacy for cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion injury(CI/RI)remains the main cause of disability and death in stroke patients due to lack of effective therapeutic strategies.One of the main issues related to CI/RI treatment is the presence of the blood-brain barrier(BBB),which affects the intracerebral delivery of drugs.Ginkgolide B(GB),a major bioactive component in commercially available products of Ginkgo biloba,has been shown significance in CI/RI treatment by regulating inflammatory pathways,oxidative damage,and metabolic disturbance,and seems to be a candidate for stroke recovery.However,limited by its poor hydrophilicity and lipophilicity,the development of GB preparations with good solubility,stability,and the ability to cross the BBB remains a challenge.Herein,we propose a combinatorial strategy by conjugating GB with highly lipophilic docosahexaenoic acid(DHA)to obtain a covalent complex GB-DHA,which can not only enhance the pharmacological effect of GB,but can also be encapsulated in liposomes stably.The amount of finally constructed Lipo@GB-DHA targeting to ischemic hemisphere was validated 2.2 times that of free solution in middle cerebral artery occlusion(MCAO)rats.Compared to the marketed ginkgolide injection,Lipo@GB-DHA significantly reduced infarct volume with better neurobehavioral recovery in MCAO rats after being intravenously administered both at 2 h and 6 h post-reperfusion.Low levels of reactive oxygen species(ROS)and high neuron survival in vitro was maintained via Lipo@GB-DHA treatment,while microglia in the ischemic brain were polarized from the pro-inflammatory M1 phenotype to the tissue-repairing M2 phenotype,which modulate neuroinflammatory and angiogenesis.In addition,Lipo@GB-DHA inhibited neuronal apoptosis via regulating the apoptotic pathway and maintained homeostasis by activating the autophagy pathway.Thus,transforming GB into a lipophilic complex and loading it into liposomes provides a promising nanomedicine strategy with excellent CI/RI therapeutic efficacy and industrialization prospects.

Selective brain hypothermia-induced neuroprotection against focal cerebral ischemia/reperfusion injury is associated with Fis1 inhibition

Selective brain hypothermia is considered an effective treatment for neuronal injury after stroke,and avoids the complications of general hypothermia.However,the mechanisms by which selective brain hypothermia affects mitochondrial fission remain unknown.In this study,we investigated the effect of selective brain hypothermia on the expression of fission 1 (Fis1) protein,a key factor in the mitochondrial fission system,during focal cerebral ischemia/reperfusion injury.Sprague-Dawley rats were divided into four groups.In the sham group,the carotid arteries were exposed only.In the other three groups,middle cerebral artery occlusion was performed using the intraluminal filament technique.After 2 hours of occlusion,the filament was slowly removed to allow blood reperfusion in the ischemia/reperfusion group.Saline,at 4℃ and 37℃,were perfused through the carotid artery in the hypothermia and normothermia groups,respectively,followed by restoration of blood flow.Neurological function was assessed with the Zea Longa 5-point scoring method.Cerebral infarct volume was assessed by 2,3,5-triphenyltetrazolium chloride staining,and apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining.Fis1 and cytosolic cytochrome c levels were assessed by western blot assay.Fis1 mRNA expression was assessed by quantitative reverse transcription-polymerase chain reaction.Mitochondrial ultrastructure was evaluated by transmission electron microscopy.Compared with the sham group,apoptosis,Fis1 protein and mRNA expression and cytosolic cytochrome c levels in the cortical ischemic penumbra and cerebral infarct volume were increased after reperfusion in the other three groups.These changes caused by cerebral ischemia/reperfusion were inhibited in the hypothermia group compared with the normothermia group.These findings show that selective brain hypothermia inhibits Fis1 expression and reduces apoptosis,thereby ameliorating focal cerebral ischemia/reperfusion injury in rats.Experiments were authorized by the Ethics Committee of Qingdao Municipal Hospital of China (approval No.2019008).

The action mechanism by which C1q/tumor necrosis factor-related protein-6 alleviates cerebral ischemia/reperfusion injury in diabetic mice

Studies have shown that C1q/tumor necrosis factor-related protein-6 (CTRP6) can alleviate renal ischemia/reperfusion injury in mice. However, its role in the brain remains poorly understood. To investigate the role of CTRP6 in cerebral ischemia/reperfusion injury associated with diabetes mellitus, a diabetes mellitus mouse model of cerebral ischemia/reperfusion injury was established by occlusion of the middle cerebral artery. To overexpress CTRP6 in the brain, an adeno-associated virus carrying CTRP6 was injected into the lateral ventricle. The result was that oxygen injury and inflammation in brain tissue were clearly attenuated, and the number of neurons was greatly reduced. In vitro experiments showed that CTRP6 knockout exacerbated oxidative damage, inflammatory reaction, and apoptosis in cerebral cortical neurons in high glucose hypoxia-simulated diabetic cerebral ischemia/reperfusion injury. CTRP6 overexpression enhanced the sirtuin-1 signaling pathway in diabetic brains after ischemia/reperfusion injury. To investigate the mechanism underlying these effects, we examined mice with depletion of brain tissue-specific sirtuin-1. CTRP6-like protection was achieved by activating the sirtuin-1 signaling pathway. Taken together, these results indicate that CTRP6 likely attenuates cerebral ischemia/reperfusion injury through activation of the sirtuin-1 signaling pathway.

Effects of “Nourishing Liver and Kidney” Acupuncture Therapy on Expression of Brain Derived Neurotrophic Factor and Synaptophysin after Cerebral Ischemia Reperfusion in Rats

The aim of the present study was to investigate the effect of ＂nourishing liver and kidney＂ acupuncture therapy on motor and cognitive deficits,and the underlying mechanism following cerebral ischemia-reperfusion（I/R） via increasing the expression of brain derived neurotrophic factor（BDNF） and synaptophysin（SYN） in the hippocampus.Healthy adult male SD rats were randomly divided into sham operation group（n=51）,model group（n=51）,acupuncture group（n=51） and acupuncture control group（n=51）.The middle cerebral I/R model was established.Acupunctures were performed in the acupuncture group and acupuncture control group at acupoints of Taixi（K103）,Taichong（ST09） of both sides,for 30 min once daily every morning.The animals in the sham operation group and model group were conventionally fed in the cage,without any intervention therapy.The rats of each group were assessed with modified neurological severity scores（m NSS）.The expression of BDNF and SYN in the hippocampus was detected by immunohistochemical SP method and the synaptic structure in hippocampus area was assessed morphologically and quantitatively at the 3rd,7th and 14 th day.The Morris water Maze（MWM） test was used to evaluate the rats＇ learning and memory abilities on the 15 th day after acupuncture.The animals in the acupuncture control group and sham operation group presented no neurological deficit.In the acupuncture group,the nerve functional recovery was significantly better than that in the model group at the 7th and 14 th day after modeling.The average MWM escape latency in the acupuncture group was shorter than that in the model group at the 3rd,4th and 5th day.The number of crossings of the platform quadrant in the acupuncture group was significantly more than that in the model group.At the each time point,the expression levels of BDNF and SYN in the hippocampal regions increased significantly in the model group as compared with the sham operation group and the acupuncture control group.In the acupuncture group,the expression levels of BDNF at the 7th and 14 th day increased more significantly than those in the model group.In the acupuncture group,the expression levels of SYN at the each time point increased more significantly than those in the model group.The post-synaptic density（PSD） was significantly increased and the synapse cleft width was narrowed in the acupuncture group as compared with other groups.The synaptic curvatures were improved obviously in the acupuncture group in contrast to the model group.It was concluded that the ＂nourishing liver and kidney＂ acupuncture therapy has positive effects on behavioral recovery,as well as learning and memory abilities,probably by promoting the expression of BDNF and SYN,and synaptic structure reconstruction in the ipsilateral hippocampus after I/R in rats.The ＂nourishing liver and kidney＂ acupuncture therapy can promote the functional recovery in rats after cerebral ischemia injury.

Therapeutic potential of stem cells in subarachnoid hemorrhage

Aneurysm rupture can result in subarachnoid hemorrhage,a condition with potentially severe consequences,such as disability and death.In the acute stage,early brain injury manifests as intracranial pressure elevation,global cerebral ischemia,acute hydrocephalus,and direct blood–brain contact due to aneurysm rupture.This may subsequently cause delayed cerebral infarction,often with cerebral vasospasm,significantly affecting patient outcomes.Chronic complications such as brain volume loss and chronic hydrocephalus can further impact outcomes.Investigating the mechanisms of subarachnoid hemorrhage-induced brain injury is paramount for identifying effective treatments.Stem cell therapy,with its multipotent differentiation capacity and anti-inflammatory effects,has emerged as a promising approach for treating previously deemed incurable conditions.This review focuses on the potential application of stem cells in subarachnoid hemorrhage pathology and explores their role in neurogenesis and as a therapeutic intervention in preclinical and clinical subarachnoid hemorrhage studies.

Traumatic brain injury and variants of shock index

Traumatic Brain Injury is a major cause of death and long-term disability.The early identification of patients at high risk of mortality is important for both management and prognosis.Although many modified scoring systems have been developed for improving the prediction accuracy in patients with trauma,few studies have focused on prediction accuracy and application in patients with traumatic brain injury.The shock index(SI)which was first introduced in the 1960s has shown to strongly correlate degree of circulatory shock with increasing SI.In this editorial we comment on a publication by Carteri et al wherein they perform a retrospective analysis studying the predictive potential of SI and its variants in populations with severe traumatic brain injury.

Transplantation of X-box-binding protein-1 gene-modified neural stem cells in the lateral ventricle of brain ischemia rats

X-box-binding protein-1 （XBP-1） is an essential transcription factor in endoplasmic reticulum stress In this study, XBP-1 gene-transfected neural stem cells （NSCs） were transplanted into lesion sites to ensure stability and persistent expression of XBP-1, resulting in the exertion of anti-apoptotic effects. Simultaneously, XBP-1 gene transfection promotes the survival and differentiation of transplanted NSCs. Results from this study demonstrated that survival, proliferation and differentiation of XBP-1 g^ne-modified NSCs were enhanced when compared to unmodified NSCs at 28 days post-transplantation （P 〈 0.05）. A diminished number of apoptotic neural cells increased Bcl-2 expression and reduced Bax expression, and were observed in the ischemic region of the XBP-1-NSCs group （P 〈 0.05）. These results indicated that modification of the XBP-1 gene enhances the survival and migration of NSCs in vivo and decreases the occurrence of apoptosis.

Expression of Bcl-2 and NF-κB in brain tissue after acute renal ischemia-reperfusion in rats

Objective:To investigate the effect of acute renal ischemia reperfusion on brain tissue.Methods:Fourty eight rats were randomly divided into four groups(n=12):sham operation group,30 min ischemia 60 min reperfusion group,60 min ischemia 60 min reperfusion group,and120 min ischemia 60 min reperfusion group.The brain tissues were taken after the experiment.TUNEL assay was used to detect the brain cell apoptosis,and western blot was used to detect the expression of apoptosis-related proteins and inflammatory factors.Results:Renal ischemiareperiusion induced apoptosis of brain tissues,and the apoptosis increased with prolongation of ischemia time.The detection at the molecular level showed decreased Bcl-2 expression,increased Bax expression,upreguiated expression of NF- κB and its downstream factor COX-2/PGE2.Conclusions:Acute renal ischemia-reperfusion can cause brain tissue damage,manifested as induced brain tissues apoptosis and inflammation activation.

Electroacupuncture reduces injury to the blood-brain barrier following cerebral ischemia/reperfusion injury

This study used electroacupuncture at Renzhong （DU26） and Baihui （DU20） in a rat model of cerebral ischemia/reperfusion injury. Neurological deficit scores, western blotting, and reverse transcription-PCR results demonstrated that electroacupuncture markedly reduced neurological deficits, decreased corpus striatum aquaporin-4 protein and mRNA expression, and relieved damage to the blood-brain barrier in a rat model of cerebral ischemia/reperfusion injury. These results suggest that electroacupuncture most likely protects the blood-brain barrier by regulating aquaporin-4 expression following cerebral ischemia/reperfusion injury.

Puerarin protects brain tissue against cerebral ischemia/reperfusion injury by inhibiting the inflammatory response

Puerarin, a traditional Chinese medicine, exerts a powerful neuroprotective effect in cerebral ischemia/reperfusion injury, but its mechanism is unknown. Here, we established rat models of middle cerebral artery ischemia/reperfusion injury using the suture method. Puerarin （100 mg/kg） was administered intraperitoneally 30 minutes before middle cerebral artery occlusion and 8 hours after reperfusion. Twenty-four hours after reperfusion, we found that puerarin significantly improved neurological deficit, reduced infarct size and brain water content, and notably diminished the expression of Toll-like receptor-4, myeloid differentiation factor 88, nuclear factor kappa B and tumor necrosis factor-α in the ischemic region. These data indicate that puerarin exerts an anti-inflammatory protective effect on brain tissue with ischemia/reperfusion damage by downregulating the expression of multiple inflammatory factors.

Pathological verification of corticospinal tract Wallerian degeneration in a rat model of brain ischemia

Although neuroimaging is commonly utilized to study Wallerian degeneration, it cannot display Wallerian degeneration early after brain injury. In the present study, we attempted to examine pathologically the process of Wallerian degeneration early after brain injury. Cerebral peduncle demyelination was observed at 3 weeks post brain ischemia, followed by demyelination in the cervical enlargement at 6 weeks. Anterograde tracing of the corticospinal tract with biotinylated dextran amine showed that following serious neurologic deficit, the tracing of the corticospinal tract of the intemal capsule, cerebral peduncle, and cervical enlargement indicated serious Wallerian degeneration.

Neuroprotective effects of autophagy inhibition on hippocampal glutamate receptor subunits after hypoxia-ischemia-induced brain damage in newborn rats

Autophagy has been suggested to participate in the pathology of hypoxic-ischemic brain damage（HIBD）.However,its regulatory role in HIBD remains unclear and was thus examined here using a rat model.To induce HIBD,the left common carotid artery was ligated in neonatal rats,and the rats were subjected to hypoxia for 2 hours.Some of these rats were intraperitoneally pretreated with the autophagy inhibitor 3-methyladenine（10 m M in 10 μL） or the autophagy stimulator rapamycin（1 g/kg） 1 hour before artery ligation.Our findings demonstrated that hypoxia-ischemia-induced hippocampal injury in neonatal rats was accompanied by increased expression levels of the autophagy-related proteins light chain 3 and Beclin-1 as well as of the AMPA receptor subunit GluR 1,but by reduced expression of GluR 2.Pretreatment with the autophagy inhibitor 3-methyladenine blocked hypoxia-ischemia-induced hippocampal injury,whereas pretreatment with the autophagy stimulator rapamycin significantly augmented hippocampal injury.Additionally,3-methyladenine pretreatment blocked the hypoxia-ischemia-induced upregulation of Glu R1 and downregulation of GluR2 in the hippocampus.By contrast,rapamycin further elevated hippocampal Glu R1 levels and exacerbated decreased GluR2 expression levels in neonates with HIBD.Our results indicate that autophagy inhibition favors the prevention of HIBD in neonatal rats,at least in part,through normalizing Glu R1 and GluR2 expression.

Naoxintong dose effects on inflammatory factor expression in the rat brain following focal cerebral ischemia

BACKGROUND： Certain components of tetramethylpyrazine, a traditional Chinese medicine, exhibit protective effects against brain injury. OBJECTIVE： To investigate the effects of different Naoxintong doses on expression of nuclear factor-kappa B （ kB）, interleukin-6, tumor necrosis factor-α, and complement 3 in rats following focal cerebral ischemia. DESIGN, TIME AND SETTING： The randomized experiment was performed at the Laboratory of Neurology, Second Hospital of Hebei Medical University from June 2004 to June 2006. MATERIALS： A total of 150 adult, healthy, male, Sprague Dawley rats, weighing 280-320g, were selected. Naoxintong powder （mainly comprising szechwan lovage rhizome, milkvetch root, danshen root, and radix angelicae sinensis） was obtained from Buchang Pharmacy Co., Ltd. in Xianyang City of Shanxi Province of China, lot number 040608. METHODS： The rats were randomly assigned into sham operation, saline, high-dose Naoxintong, moderate-dose Naoxintong, and low-dose Naoxintong groups, with 30 rats in each group. Rat models of middle cerebral artery occlusion were established using the suture method, with the exception of the sham operation group. Rats in the high-dose, moderate-dose and low-dose Naoxintong groups received 4, 2, and 1 g/kg Naoxintong respectively, by gavage. Rats in the saline group were treated with 1 mL saline by gavage All rats were administered by gavage at 5 and 23 hours following surgery, and subsequently, once per day. MAIN OUTCOME MEASURES： At 6, 24, 48, 72 hours, and 7 days following model establishment, brain water content was measured. Histopathological changes in brain tissues were detected using hematoxylin-eosin staining. Expression of nuclear factor- kB, interleukin-6, tumor necrosis factor- α, and complement 3 was examined by immunohistochemistry. RESULTS： A total of 150 rats were included in the final analysis with no loss. Brain water content was significantly increased in the ischemic hemisphere of rats from the saline, as well as the high-dose, moderate-dose, and low-dose Naoxintong groups at 24 hours, which reached a peak at 48 hours. At 6, 24, 48, 72 hours, and 7 days, brain water content was greater in the ischemic hemisphere of rats from the saline, as well as the high-dose, moderate-dose, and low-dose Naoxintong groups, compared with the sham operation group （P 〈 0.05）. At 24 and 48 hours, brain water content was reduced in the high-dose and moderate-dose Naoxintong groups, compared to the saline and low-dose Naoxintong groups （P 〈 0.05）. In the saline, as well as high-dose, moderate-dose, and low-dose Naoxintong groups, neuronal edema was observed at 6 hours surrounding the ischemic sites. Inflammatory cells appeared at 24 hours, reached a peak at 48 hours, and gradually diminished. A small amount of glial cell proliferation and neuronal degeneration were observed in the hippocampus at 72 hours following infarction. Microglial proliferation and aggregation were detected at 7 days after infarction. Expression of nuclear factor- kB, interleukin-6, tumor necrosis factor-α, and complement 3 was significantly less in the high-dose, moderate-dose, and low-dose Naoxintong groups, compared to the sham operation group （P 〈 0.05）. Expression of the above-mentioned inflammatory cytokines was lower in rat brain tissues of the high-dose Naoxintong group, compared to the low-dose Naoxintong group （P 〈 0.05）. CONCLUSION： High-dose Naoxintong and moderate-dose Naoxintong significantly alleviated rat brain edema and decreased expression of nuclear factor-kB, interleukin-6, tumor necrosis factor-α, and complement 3 in brain tissues. The protective effect of high-dose Naoxintong was most significant.

Influence of hypoxia-inducible factor 1-alpha on neuronal apoptosis in a rat model of hypoxia-or hypoxia-ischemia-induced brain injury

BACKGROUND： In addition to neuroprotective genes, the targeted genes of hypoxia-inducible factor 1α （HIF-1α） include pro-apoptotic genes. However, the influence of HIF-1α on neuronal apoptosis in hypoxia-ischemia remains poorly understood. OBJECTIVE： To investigate the relationship between HIF-1α expression and neuronal apoptosis in hypoxia or hypoxia-ischemia brain injury and to determine the role of HIF-1α in regulating neuronal apoptosis. DESIGN, TIME AND SETTING： A randomized, controlled animal experiment was performed at the Laboratory of Children Neurology of Sichuan University between May 2006 and May 2007. MATERIALS： In situ cell death detected kit was provided by Roche, USA; rabbit anti-mouse HIF-1α polyclonal antibody was purchased from Santa Cruz Biotechnologies, USA; rabbit anti-mouse cleaved caspase-3 polyclonal antibody was purchased from Chemicon, USA. METHODS： A total of 36 Sprague Dawley rats aged 10 days were randomly assigned to 3 groups： sham-surgery, hypoxia, and hypoxia-ischemia, with 12 rats per group. The rats were treated at 3 time points： 4, 8, and 24 hours, with 4 rats per time point. In the hypoxia-ischemia group, the right common carotid artery was exposed and permanently ligated through a midline cervical incision. A 2.5-hour exposure to hypoxia （8% O2/92% N2） was used to induce hypoxia-ischemia injury. In the hypoxia group, rats were exposed to hypoxia without ligation of the common carotid artery. In the sham-surgery group, the common carotid artery was exposed without ligation or hypoxia. MAIN OUTCOME MEASURES： Histopathological changes, HIF-1α and activated caspase-3 protein expression, integrated optical density of positive cells, and apoptosis-positive cells. RESULTS： Hematoxylin and eosin staining showed that neuronal degeneration and edema was most prominent at 24 hours after hypoxia-ischemia. HIF-1α protein expression was significantly upregulated at 4 hours, peaked at 8 hours, and decreased at 24 hours after hypoxia or hypoxia-ischemia. HIF-1α protein expression was significant greater in the hypoxia and hypoxia-ischemia groups compared with the sham-surgery group （P 〈 0.01）. Activated caspase-3 protein expression began to increase at 4 and 8 hours following hypoxia or hypoxia-ischemia and was significantly upregulated at 24 hours. Activated caspase-3 protein expression remained at low levels in the sham controls compared with the hypoxia and hypoxia-ischemia groups （P〈 0.01）. TUNEL staining showed that the number of apoptotic cells significantly increased at 24 hours after hypoxia or hypoxia-ischemia. In addition, HIF-1α protein expression was greater in the hypoxia group compared with the hypoxia-ischemia group at the same time point （P 〈 0.05）. However, activated caspase-3 expression and the number of TUNEL-positive cells were less in the hypoxia group compared with the hypoxia-ischemia group at the same time point （P〈 0.05）. CONCLUSION： HIF-1α played a neuroprotective role following hypoxia-ischemia brain injury.

Constraint-induced movement therapy promotes motor function recovery and downregulates phosphorylated extracellular regulated protein kinase expression in ischemic brain tissue of rats

Motor function impairment is a common outcome of stroke.Constraint-induced movement therapy（CIMT）involving intensive use of the impaired limb while restraining the unaffected limb is widely used to overcome the effects of＇learned non-use＇and improve limb function after stroke.However,the underlying mechanism of CIMT remains unclear.In the present study,rats were randomly divided into a middle cerebral artery occlusion（model）group,a CIMT＋model（CIMT）group,or a sham group.Restriction of the affected limb by plaster cast was performed in the CIMT and sham groups.Compared with the model group,CIMT significantly improved the forelimb functional performance in rats.By western blot assay,the expression of phosphorylated extracellular regulated protein kinase in the bilateral cortex and hippocampi of cerebral ischemic rats in the CIMT group was significantly lower than that in the model group,and was similar to sham group levels.These data suggest that functional recovery after CIMT may be related to decreased expression of phosphorylated extracellular regulated protein kinase in the bilateral cortex and hippocampi.

Toll-like receptor 4 as a possible therapeutic target for delayed brain injuries after aneurysmal subarachnoid hemorrhage

Neuroinflammation is a well-recognized consequence of subarachnoid hemorrhage（SAH）, and Toll-like receptor（TLR） 4 may be an important therapeutic target for post-SAH neuroinflammation. Of the TLR family members, TLR4 is expressed in various cell types in the central nervous system, and is unique in that it can signal through both the myeloid differentiation primary-response protein 88-dependent and the toll receptor associated activator of interferon-dependent cascades to coordinate the maximal inflammatory response. TLR4 can be activated by many endogenous ligands having damage-associated molecular patterns including heme and fibrinogen at the rupture of an intracranial aneurysm, and the resultant inflammatory reaction and thereby tissue damages may furthermore activate TLR4. It is widely accepted that the excreted products of TLR4 signaling alter neuronal functions. Previous studies have focused on the pathway through nuclear factor（NF）-κΒ signaling among TLR4 signaling pathways as to the development of early brain injury（EBI） such as neuronal apoptosis and blood-brain barrier disruption, and cerebral vasospasm. However, many findings suggest that both pathways via NF-κΒ and mitogen-activated protein kinases may be involved in EBI and cerebral vasospasm development. To overcome EBI and cerebral vasospasm is important to improve outcomes after SAH, because both EBI and vasopasm are responsible for delayed brain injuries or delayed cerebral ischemia, the most important preventable cause of poor outcomes after SAH. Increasing evidence has shown that TLR4 signaling plays an important role in SAH-induced brain injuries. Better understanding of the roles of TLR4 signaling in SAH will facilitate development of new treatments.

Magnetic resonance imaging tracing of transplanted bone marrow mesenchymal stem cells in a rat model of cardiac arrest-induced global brain ischemia

BACKGROUND： Numerous studies have shown that magnetic resonance imaging （MRI） can detect survival and migration of super paramagnetic iron oxide-labeled stem cells in models of focal cerebral infarction. OBJECTIVE： To observe distribution of bone marrow mesenchymal stem cells （BMSCs） in a rat model of global brain ischemia following cardiac arrest and resuscitation, and to investigate the feasibility of tracing iron oxide-labeled BMSCs using non-invasive MRI. DESIGN, TIME AND SETTING： The randomized, controlled, molecular imaging study was performed at the Linbaixin Medical Research Center, Second Affiliated Hospital, Sun Yat-sen University, and the Institute of Cardiopulmonary Cerebral Resuscitation, Sun Yat-sen University, China from October 2006 to February 2009. MATERIALS： A total of 40 clean, Sprague Dawley rats, aged 6 weeks and of either gender, were supplied by the Experimental Animal Center, Sun Yat-sen University, China, for isolation of BMSCs. Feridex （iron oxide）, Gyroscan Inetra 1.5T MRI system, and cardiopulmonary resuscitation device were used in this study. METHODS： A total of 30 healthy, male Sprague Dawiey rats, aged 6 months, were used to induce ventricular fibrillation using alternating current. After 8 minutes, the rats underwent 6-minute chest compression and mechanical ventilation, followed by electric defibrillation, to establish rat models of global brain ischemia due to cardiac arrest and resuscitation. A total of 24 successful models were randomly assigned to Feridex-labeled and non-labeled groups （n = 12 for each group）. At 2 hours after resuscitation, 5 ×10^8 Feridex-labeled BMSCs, with protamine sulfate as a carrier, and 5 ×10^6 non-labeled BMSCs were respectively transplanted into both groups of rats through the right carotid artery （cells were harvested in 1 mL phosphate buffered saline）. MAIN OUTCOME MEASURES： Feridex-labeled BMSCs were observed by Prussian blue staining and electron microscopy. Signal intensity, celluar viability, and proliferative capacity of BMSCs were measured using MRI, Trypan blue test, and M-IT assay, respectively. Distribution of transplanted cells was observed in rats utilizing MRI and Prussian blue staining prior to and 1, 3, 7, and 14 days after transplantation. RESULTS： Prussian blue staining displayed many blue granules in the Feridex-labeled BMSCs. High density of iron granules was observed in the cytoplasm under electron microscopy. According to MRI results, and compared with the non-labeled group, the signal intensity was decreased in the Feridex-labeled group （P 〈 0.05）. The decrease was most significant in the 50 pg/mL Feridex-labeled group （P 〈 0.01）. There were no significant differences in celluar viability and proliferation of BMSCs between the Feridex-labeled and non-labeled groups after 1 week （P 〉 0.05）. Low-signal lesions were detected in the rat hippocampus and temporal cortex at 3 days after transplantation. The low-signal lesions were still detectable at 14 days, and positively stained cells were observed in the hippocampus and temporal cortex using Prussian blue staining. There were no significant differences in signal intensity in the non-labeled group. CONCLUSION： BMSC transplantation traversed the blood-brain barrier and distributed into vulnerable zones in a rat model of cardiac arrest-induced global brain ischemia. MRI provided a non-invasive method to in vivo dynamically and spatially trace Feridex-labeled BMSCs after transplantation.

Brain-derived neurotrophic factor inhibits glucose intolerance after cerebral ischemia

Brain-derived neurotrophic factor is associated with the insulin signaling pathway and glucose me- tabolism. We hypothesized that expression of brain-derived neurotrophic factor and its receptor may be involved in glucose intolerance following ischemic stress. To verify this hypothesis, this study aimed to observe the changes in brain-derived neurotrophic factor and tyrosine kinase B receptor expression in glucose metabolism-associated regions following cerebral ischemic stress in mice. At day 1 after middle cerebral artery occlusion, the expression levels of brain-derived neurotrophic factor were significantly decreased in the ischemic cortex, hypothalamus, liver, skeletal muscle, and pancreas. The expression levels of tyrosine kinase B receptor were decreased in the hypothalamus and liver, and increased in the skeletal muscle and pancreas, but remained unchanged in the cortex Intrahypothalamic administration of brain-derived neurotrophic factor （40 ng） suppressed the de- crease in insulin receptor and tyrosine-phosphorylated insulin receptor expression in the liver and skeletal muscle, and inhibited the overexpression of gluconeogenesis-associated phosphoenolpy- ruvate carboxykinase and glucose-6-phosphatase in the liver of cerebral ischemic mice. However, serum insulin levels remained unchanged. Our experimental findings indicate that brain-derived neurotrophic factor can promote glucose metabolism, reduce gluconeogenesis, and decrease blood glucose levels after cerebral ischemic stress. The low expression of brain-derived neurotrophic factor following cerebral ischemia may be involved in the development of glucose intolerance.

Phosphorylation of tau protein over time in rats subjected to transient brain ischemia

Transient brain ischemia has been shown to induce hyperphosphorylation of the micro- tubule-associated protein tau. To further determine the mechanisms underlying these processes, we investigated the interaction between tau, glycogen synthase kinase （GSK）-313 and protein phos- phatase 2A. The results confirmed that tau protein was dephosphorylated during brain ischemia; in addition, the activity of GSK-3β was increased and the activity of protein phosphatase 2A was de- creased. After reperfusion, tau protein was hyperphosphorylated, the activity of GSK-3β was de- creased and the activity of protein phosphatase 2A remained low. Importantly, the interaction of tau with GSK-3β and protein phosphatase 2A was altered during ischemia and reperfusion. Lithium chloride could affect tau phosphorylation by regulating the interaction of tau with GSK-3β and pro- tein phosphatase 2A, and improve learning and memory ability of rats after transient brain ischemia. The present study demonstrated that it was the interaction of tau with GSK-3β and protein phos- phatase 2A, rather than their individual activities, that dominates the phosphorylation of tau in tran- sient brain ischemia. Hyperphosphorylated tau protein may play an important role in the evolution of brain injury in ischemic stroke. The neuroprotective effects of lithium chloride partly depend on the inhibition of tau phosphorylation during transient brain ischemia.