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.

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.

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.

The role of glycogen synthase kinase 3 beta in brain injury induced by myocardial ischemia/reperfusion injury in a rat model of diabetes mellitus

Myocardial ischemia/reperfusion injury can lead to severe brain injury.Glycogen synthase kinase 3 beta is known to be involved in myocardial ischemia/reperfusion injury and diabetes mellitus.However,the precise role of glycogen synthase kinase 3 beta in myocardial ischemia/reperfusion injury-induced brain injury is unclear.In this study,we observed the effects of glycogen synthase kinase 3 beta on brain injury induced by myocardial ischemia/reperfusion injury in diabetic rats.Rat models of diabetes mellitus were generated via intraperitoneal injection of streptozotocin.Models of myocardial ischemia/reperfusion injury were generated by occluding the anterior descending branch of the left coronary artery.Post-conditioning comprised three cycles of ischemia/reperfusion.Immunohistochemical staining and western blot assays demonstrated that after 48 hours of reperfusion,the structure of the brain was seriously damaged in the experimental rats compared with normal controls.Expression of Bax,interleukin-6,interleukin-8,terminal deoxynucleotidyl transferase d UTP nick end labeling,and cleaved caspase-3 in the brain was significantly increased,while expression of Bcl-2,interleukin-10,and phospho-glycogen synthase kinase 3 beta was decreased.Diabetes mellitus can aggravate inflammatory reactions and apoptosis.Ischemic post-conditioning with glycogen synthase kinase 3 beta inhibitor lithium chloride can effectively reverse these changes.Our results showed that myocardial ischemic post-conditioning attenuated myocardial ischemia/reperfusion injury-induced brain injury by activating glycogen synthase kinase 3 beta.According to these results,glycogen synthase kinase 3 beta appears to be an important factor in brain injury induced by myocardial ischemia/reperfusion injury.

Expression of netrin-1 and its receptors, deleted in colorectal cancer and uncoordinated locomotion-5 homolog B, in rat brain following focal cerebral ischemia reperfusion injury

Netrin-1 is currently one of the most highly studied axon guidance factors. Netrin-1 is widely expressed in the embryonic central nervous system, and together with the deleted in colorectal cancer and uncoordinated locomotion-5 homolog B receptors, netrin-1 plays a guiding role in the construction of neural conduction pathways and the directional migration of neuronal cells. In this study, we established a rat middle cerebral artery ischemia reperfusion model using the intraluminal thread technique. Immunofluorescence microscopy showed that the expression of netrin-1 and deleted in colorectal cancer in the ischemic penumbra was upregulated at 1 day after reperfusion, reached a peak at 14 days, and decreased at 21 days. There was no obvious change in the expression of uncoordinated locomotion-5 homolog B during this time period. Double immunofluorescence labeling revealed that netrin-1 was expressed in neuronal cells and around small vessels, but not in astrocytes and microglia, while deleted in colorectal cancer was localized in the cell membranes and protrusions of neurons and astrocytes. Our experimental findings indicate that netrin-1 may be involved in post-ischemic repair and neuronal protection via deleted in colorectal cancer receptors.

Increased expression of receptor for advanced glycation end-products worsens focal brain ischemia in diabetic rats

A rat model of diabetes mellitus was induced by a high fat diet, followed by focal brain ischemia induced using the thread method after 0.5 month. Immunohistochemistry showed that expression of receptor for advanced glycation end-products was higher in the ischemic cortex of diabetic rats compared with non-diabetic rats with brain ischemia. Western blot assay revealed increased phosphorylated c-Jun N-terminal kinase expression, and unchanged phosphorylated extracellular signal-regulated protein kinase protein expression in the ischemic cortex of diabetic rats compared with non-diabetic rats with brain ischemia. Additionally, phosphorylated p38 mitogen-activated protein kinase protein was not detected in any rats in the two groups. Severity of limb hemiplegia was worse in diabetic rats with brain ischemia compared with ischemia alone rats. The results suggest that increased expression of receptor for advanced glycation end-products can further activate the c-Jun N-terminal kinase pathway in mitogen-activated protein kinase, thereby worsening brain injury associated with focal brain ischemia in diabetic rats.

Effects of Chuanxiongqin hydrochloride on increasing the fluidity of brain cell membrane and scavenging free radicals in model rats with ischemia/reperfusion injury

BACKGROUND: The fluidity of cell membrane can be affected by various factors. Many experiments have confirmed that the ischemia/reperfusion of organic tissue can increase the contents of free radicals, which lead to high rigidity and low fluidity of cell membrane, and the conditions can be changed by Chuanxiongqin. OBJECTIVE: To observe the effect and mechanism of Chuanxiongqin hydrochloride on the fluidity of brain cell membrane in rat models of ischemia/reperfusion. DESIGN: A completely randomized controlled animal trial. SETTINGS: Institute of Brain Sciences; Department of Physiology, Medical College, Datong University. MATERIALS: Twenty male grade Ⅰ Wistar rats of 170-220 g were randomly divided into model group (n =10) and control group (n =10). Chuanxiongqin hydrochloride (molecular mass was 172.2) was purchased from the National Institute for the Control of Pharmaceutical and Biological Products (batch number: 0817-9803); Spin labelers: 5-doxyl-stearlic acid methylester (5DS), 16-doxyl-stearlic acid methylester (16DS), xanthine, xanthine oxidase (XOD) and 5,5-dimeth-1-pyrroline- N-oxide (DMPO) from Sigma Company; Bruker ESP 300 electron paramagnetic resonance (EPR) spectrometer by Bruker Company (Germany). METHODS: The experiments were carried out in the State Key Laboratory of Natural and Biomimetic Drugs, Peking University from June 2001 to July 2002. In the model group, rats were made into models of cerebral ischemia by 30-minute ligation and 2-hour reperfusion of common carotid arteries; The rats in the control group were not made into models. The order parameter (S) and rotational correlation time (τc) were detected with the ESR spectrometer by means of spin labeling. The greater the S and τc, the smaller the fluidity. Meanwhile, the clearance rate of free radicals was detected with ESR spin trapping. The measurement data were compared using the t test. MAIN OUTCOME MEASURES: The S, τc and clearance rates of O2 · and OH· free radicals were compared between the model group and control group. RESULTS: The S and τc in the model group [0.738 4±0.003 5; (8.472±0.027)×10-10 s/circle] were obviously different from those in the control group [0.683 9±0.008 3; (7.945±0.082)×10-10 s/circle, t =5.731, 5.918, P < 0.05], which suggested that ischemia/reperfusion injury decreased the fluidity of brain cell membrane. After adding Chuanxiongqin hydrochloride, there were no obvious differences between the model group [0.688 5±0.030 5; (7.886±0.341)×10-10 s/circle] and control group (P > 0.05), indicating that Chuanxiongqin hydrochloride could recover the fluidity of brain cell membrane after ischemia/reperfusion injury close to the level in the normal control group. Chuanxiongqin hydrochloride could directly scavenge the O2 · and OH· free radicals, and the maximal clearance rates were 83.92% and 44.99% respectively. CONCLUSION: Chuanxiongqin hydrochloride increases the fluidity of membrane of ischemia-injured brain cell by scavenging both O2 ·and OH· free radicals.

Editor's Choice——Acupuncture and neural regeneration after brain ischemia

Acupuncture at acupoints can improve the functions of distal organs. Neuropathological studies have shown that electroacupuncture can significantly reduce the infarct volume, and improve the proportions of injured corpus striatum cells and residual cortical cells. Acupuncture-like sense stimulation can activate various conduction pathways that induce changes in nervous system activities.

The Influence of Remote Ischemic Conditioning on Focal Brain Ischemia in Rats

Despite obvious progress in the treatment of acute forms of ischemic stroke, the risk of this condition remains unacceptably high. Brain infarction in the middle cerebral artery basin occurs in patients with atherosclerosis. The onset of the brain infarction is facilitated by the cessation of circulation (embolism) in conditions of insufficient collateral circulation. The extent of the infarct zone is determined by neuronal death and impaired microcirculation. The development of new methods for effective targeted restorative stroke therapy is crucial for restorative treatment and reducing the risk of mortality after stroke. Remote ischemic conditioning (RIC) is an approach to limiting reperfusion injury in the ischemic region of the brain after focal ischemia. One of the most commonly used in vivo models in stroke studies is the filament model of Middle Cerebral Artery Occlusion (MCAO) in rats. In our experiment, it was performed for 30 min (J. Koizumi) with subsequent 48-hour reperfusion. Within the first 24 hours after the start of reperfusion several short episodes of ischemia in low limbs were induced. After 48 hours of reperfusion the brains were harvested and stained with TTC. Then we evaluated the effect of RIC within 24 hours ex vivo in rats’ brains, as well as syndecan-1 plasma concentration. Infarct area was assessed by means of Image-Pro program with statistical analysis. Infarct volumes in the model group (31.97% ± 2.5%) were significantly higher compared to the values in the RIC group 48 hours after ischemia-reperfusion (13.6% ± 1.3%) (*P < 0.05). A significant reduction in the area of infarction after RIC is likely due to the effect on the regulation of collateral blood flow in the ischemia area. On the second day after ischemia-reperfusion, tissue swelling was reduced in the RIC group compared to the model group. Analysis of the average concentration of Syndecan-1 revealed the difference between model and RIC groups. Syndecan-1, endothelial glycocalyx protein, might be the regulator which performs vascular control of the interaction with inflammatory cell and is responsible for mediate effect of remote ischemic conditioning on the restriction of ischemic-reperfusion injury.

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).

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.

A feasible strategy for focal cerebral ischemiareperfusion injury: remote ischemic postconditioning

It is difficult to control the degree of ischemic postconditioning in the brain and other isch- emia-sensitive organs. Remote ischemic postconditioning could protect some ischemia-sensitive organs through measures on terminal organs. In this study, a focal cerebral ischemia-reperftlsion injury model was established using three cycles of remote ischernic postconditioning, each cycle consisted of 10-minute occlusion of the femoral artery and 10-minute opening. The results showed that, remote ischemic postconditioning significantly decreased the percentage of the in- farct area and attenuated brain edema. In addition, inflammatory nuclear factor-KB expression was significantly lower, while anti-apoptotic Bcl-2 expression was significantly elevated in the ce- rebral cortex on the ischemic side. Our findings indicate that remote ischemic postconditioning attenuates focal cerebral ischemia/reperfusion injury, and that the neuroprotective mechanism is mediated by an anti-apoptotic effect and reduction of the inflammatory response.

Influence of Ren and Du meridian electro-acupuncture on neural stem cell proliferation and extracellular signal-regulated kinase pathway in a rat model of focal cerebral ischemia injury

BACKGROUND： Studies have shown that electro-acupuncture at the Ren meridian could improve proliferation of subventricular zone neural stem cells in cerebral-ischemic rats. However, there are few reports on the influence of electro-acupuncture at the Du meridian on neural stem cell proliferation. OBJECTIVE： To observe the influence of electro-acupuncture at Ren and Du meridians on neural stem cell proliferation in the subventricular zone and altered signal transduction in cerebral ischemia rats. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Laboratory of Human Anatomy, Medical College of Sun Yat-sen University from May 2006 to February 2008. MATERIALS： Mouse anti-rat bromodeoxyuridine （BrdU） monoclonal antibody was provided by Sigma, USA; mouse anti-rat nestin monoclonal antibody and extracellular signal-regulated protein kinase （ERK） specific inhibitor PD98059 were provided by Calbiochem, Germany; acupuncture needle was provided by Suzhou Acupuncture Supplies, China. METHODS： A total of 126 rats were randomly assigned to four groups： model （n = 36）, Du meridian （n = 36）, Ren/Du meridian （n = 36）, and Ren/Du meridian ＋ PD98059 （n = 18）. Rats in the Ren/Du meridian ＋ PD98059 group were observed on days 7 （n = 6） and 14 （n = 12） after cerebral ischemia injury. Rats in the model, Du meridian, and Ren/Du meridian groups were observed on days 7, 14, and 28 after cerebral ischemia injury, with 12 rats per group at each time point. Thread occlusion was used to establish middle cerebral artery occlusion models. Electro-acupuncture was performed at Renzhong （DU 26） and Baihui （DU 20） acupoints in the Du meridian group, as well as Chengjiang （RN 24）, Guanyuan （RN 4）, Renzhong, and Baihuiacupoints in the Ren/Du meridian and Ren/Du meridian ＋ PD98059 groups 2 days after model establishment. In addition, electro-acupuncture stimulation with disperse-dense waves was performed, with 30 Hz disperse wave, 100 Hz dense wave, and 5 V intensity for 20 minutes. Rats in the Ren/Du meridian ＋ PD98059 group were treated with 0.2 pg PD98059 injection into the subventricular zone, 2 pL per rat. Rats in the model group were not treated with electro-acupuncture. MAIN OUTCOME MEASURES： BrdU/nestin immunofluorescent staining was used to detect proliferating neural stem cells in the subventricular zone of cerebral ischemia rats; Western blot was used to determine phosphorylated ERK1 and 2 （pERK1/2） expression in the subventricular zone. RESULTS： On days 14 and 28 after cerebral ischemia, there were significantly more BrdU-positive and BrdU/nestin-positive cells in the Ren/Du meridian group compared with the Du meridian group （P 〈 0.05）. PD98059 decreased the number of BrdU-positive and BrdU/nestin-positive cells induced by electro-acupuncture at the/：ten and Du meridians （P 〈 0.05）. On days 7, 14, and 28 after treatment, pERK1/2 expression was significantly greater in the Du meridian and Ren/Du meridian groups compared with the model group （P 〈 0.05）. The promoting effect of electro-acupuncture at Ren and Du meridians on ERK1/2 phosphorylation was superior to electro-acupuncture at the Du meridian alone on day 14 after model induction （P 〈 0.05）. However, PD98059 completely abolished the promoting effect of electro-acupuncture at Ren/Du meridians on pERK1/2 expression （P 〈 0.05）. CONCLUSION： Electro-acupuncture at Ren and Du meridians increased proliferation of subventricular zone neural stem cells, which was related to activation of the ERK pathway in a rat model of cerebral ischemia injury.

Migration and differentiation of bone marrow-derived multipotent adult progenitor cells through tail vein injection in a rat model of cerebral ischemia

BACKGROUND： Multipotent adult progenitor cells （MAPCs） from the bone marrow have been shown to differentiate into neurons. OBJECTIVE： To observe migration, survival, and neuronal-like differentiation of MAPCs by tail vein injection. DESIGN, TIME AND SETTING： Randomized, controlled experiment of neural tissue engineering was performed at the Laboratory for Cardio-Cerebrovascular Disease, Hospital of Integrated Traditional and Western Medicine, Tongji Medical College of Huazhong University of Science and Technology between September 2006 and August 2007. MATERIALS： Eighty Sprague Dawley rats, 3-6 months old, underwent cerebral ischemia/reperfusion by thread technique, and were randomly divided into model and MAPCs groups （n = 40）. METHODS： Mononuclear cells were harvested from bone marrow using the FicolI-Paque density gradient centrifugation method. After removing CD45 and glycophorin A-positive cells （GLYA＋） with immunomagnetic beads, CD45 GLYA adult progenitor cells were labeled with bromodeoxyuridine （5-bromo-2-deoxyuridine, BrdU）. A total of 1 mL cell suspension, containing 5 × 10^6 MAPCs, was injected into the MAPCs group through the tail vein. A total of 1 mL normal saline was injected into the model rats. MAIN OUTCOME MEASURES： After 60 days, BrdU and neuron-specific enolase double-positive cells were observed using immunofluorescence. Cell morphology was observed under electron microscopy, and nerve growth factor mRNA was measured through RT-PCR. In addition, rat neurological functions were measured with behavioral tests. RESULTS： Immunofluorescence revealed that MAPCs positive for BrdU and neuron specific enolase were found surrounding the ischemic focus in the MAPCs group. Microscopic observation suggested that MAPCs-derived neuronal-like cells connected with other nerve cells to form synapses. Compared with the model animals, the level of nerve growth factor mRNA was significantly upregulated in rats injected with MAPCs （P 〈 0.05）. In addition, rats in the MAPCs group performed better in behavioral tests than the model group on days 28 and 60 （P 〈 0.05）. CONCLUSION： Transplanted MAPCs migrated to the ischemic region, survived, and differentiated into neuronal-like cells, resulting in stimulation of nerve growth factor mRNA and improved neurological function in ischemic rats.

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.

Regulation of extracellular signal-regulated kinase 1/2 influences hippocampal neuronal survival in a rat model of diabetic cerebral ischemia

Activation of extracellular signal-regulated kinase 1/2 has been demonstrated in acute brain ischemia. We hypothesized that activated extracellular signal-regulated kinase 1/2 can protect hippocampal neurons from injury in a diabetic model after cerebral ischemia/reperfusion. In this study, transient whole-brain ischemia was induced by four-vessel occlusion in normal and diabetic rats, and extracellular signal-regulated kinase 1/2 inhibitor （U0126） was administered into diabetic rats 30 minutes before ischemia as a pretreatment. Results showed that the number of surviving neurons in the hippocampal CA1 region was reduced, extracellular signal-regulated kinase 1/2 phosphorylation and KuT0 activity were decreased, and pro-apoptotic Bax expression was upregulated after intervention using U0126. These findings demonstrate that inhibition of extracellular signal-regulated kinase 1/2 activity aggravated neuronal loss in the hippocampus in a diabetic rat after cerebral ischemia/reperfusion, further decreased DNA repairing ability and ac- celerated apoptosis in hippocampal neurons. Extracellular signal-regulated kinase 1/2 activation plays a neuroprotective role in hippocampal neurons in a diabetic rat after cerebral ischemia/ reperfusion.

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.

Is longer sevoflurane preconditioning neuroprotective in permanent focal cerebral ischemia?

Sevoflurane preconditioning has neuroprotective effects in the cerebral ischemia/reperfusion model. However, its influence on permanent cerebral ischemia remains unclear. In the present study, the rats were exposed to sevoflurane for 15, 30, 60, and 120 minutes, followed by induction of perma- nent cerebral ischemia. Results demonstrated that 30- and 60-minute sevoflurane preconditioning significantly reduced the infarct volume at 24 hours after cerebral ischemia, and 60-minute se- voflurane preconditioning additionally reduced the number of TUNEL- and caspase-3-positive cells in the ischemic penumbra. However, 120-minute sevoflurane preconditioning did not show evident neuroprotective effects. Moreover, 60-minute sevoflurane preconditioning significantly attenuated neurological deficits and infarct volume in rats at 4 days after cerebral ischemia. These findings in- dicated that 60-minute sevoflurane preconditioning can induce the best neuroprotective effects in rats with permanent cerebral ischemia through the inhibition of apoptosis.