Diabetic retinopathy is a leading cause of acquired blindness, and it is the most common ischemic disorder of the retina. Available treatments are not very effective. Efforts to inhibit diabetic reti- nopathy have foc...Diabetic retinopathy is a leading cause of acquired blindness, and it is the most common ischemic disorder of the retina. Available treatments are not very effective. Efforts to inhibit diabetic reti- nopathy have focused either on highly specific therapeutic approaches for pharmacologic targets or using genetic approaches to change expression of certain enzymes. However, it might be wise to choose innovative treatment modalities that act by multiple potential mechanisms. The resis- tance to ischemic injury, or ischemic tolerance, can be transiently induced by prior exposure to a non-injurious preconditioning stimulus. A complete functional and histologic protection against retinal ischemic damage can be achieved by previous preconditioning with non-damaging isch- emia. In this review, we will discuss evidence that supports that ischemic conditioning could help avert the dreaded consequences that results from retinal diabetic damage.展开更多
BACKGROUND： Hypoxia inducible factor-1 alpha （HIF-1 （x） and erythropoietin（EPO）, possessing neuroprotective effect in the cerebral ischemia, might play an important role in the formation of cerebral ischemic tol...BACKGROUND： Hypoxia inducible factor-1 alpha （HIF-1 （x） and erythropoietin（EPO）, possessing neuroprotective effect in the cerebral ischemia, might play an important role in the formation of cerebral ischemic tolerance （IT）. OBJECTIVE：To observe the neuroprotective effect of cerebral ischemic preconditioning（IPC） of rats, and the expression and mechanism of HIF-1α and target gene erythropoietin in the brain tissue following the formation of cerebral IT. DESIGN ： A randomized and controlled observation SETTING： Department of Neurology, the Affiliated Hospital of Medical College, Qingdao University MATERIALS： Totally 84 enrolled adult healthy male Wistar rats of clean grade, weighing 250 to 300 g, were provided by the Animal Experimental Department, Tongji Medical College of Huazhong University of Science and Technology. Ready-to-use SABC reagent kit and rabbit anti-rat HIF-1α monoclonal antibody were purchased from Boshide Bioengineering Co.Ltd （Wuhan）; Rabbit anti-rat EPO monoclonal antibody was purchased from Santa Cruz Company （USA）. METHODS： This experiment was carried out in the Department of Anatomy, Medical College, Qingdao University during March 2005 to March 2006. ① The 84 rats were divided into 3 groups by a lot： IPC group （n=40）, sham-operation group （n=40） and control group （n=4）. In the IPC group, middle cerebral artery was occluded for 2 hours respectively on the 1^st, 3^rd, 7^th, 14^th and 21^st days of the reperfusion following 10-minute preischemia was made using a modified middle cerebral artery second suture method from Zea-Longa. The rats were sacrificed 22 hours after reperfusion in the end of middle cerebral artery occlusion （MCAO）. That was to say, after 10-minute preischemia, suture was exited to the extemal carotid artery and embedded subcutaneously. Middle cerebral artery was occluded again to form the second reperfusion at the set time point after reperfusion. Twenty-two hours later, rats were sacrificed; In the sham-operation group,the preischemia was substituted by sham-operation（only common carotid artery and crotch were exposed, and MCAO by suture was omitted）, and the other procedures were the same as those in the IPC group. In the control group, rats were given sham-operation twice at an interval of one day, and they were sacrificed 24 hours after the second sham-operation. ② Brain tissue was taken from the rats in each group. Cerebral infarction area of each layer was measured with TTC staining, and total cerebral infarction volume （The total cerebral infarction area of each layerxinterspace ） was calculated. After brain tissue was stained by haematoxylin-esoin （HE）, the form of nerve cells was observed under an optical microscope, and the expressions of HIF-1α（and EPO protein in the brain tissue were detected with immunohistochemical method. MAIN OUTCOME MEASURES： ①Cerebral infarction volume;②form of nerve cell; ③ the expression of HIF-1α and EPO protein in the brain tissue. RESULTS：Totally 84 rats were enrolled in the experiment. The dead rats were randomly supplied during the experiment, and finally 84 rats entered the stage of result analysis. ① Detection of cerebral infarction volume of rats in each group： Cerebral infarction volume in the IPC group was significantly smaller than that in the sham-operation group on the 1^st, 3^rd and 7^th days after reperfusion respectively [（161.2±6.9） mm^3 vs （219.9±11.2） mm^3, （134.9±9.0） mm^3 vs （218.6±13.0） mm^3, （142.9±13.7） mm^3 vs （221.3±14.2） mm^3, t=-8.924, 10.587,7.947, P〈 0.01]. ② Observation of nerve cell form of brain tissue： HE staining showed that the ischemic degree, range and cerebral edema degree of IPC group were significantly milder than those of sham-operation group. ③ The expressions of HIF-1α and EPO protein in cerebral cortex and hippocampus ： The expression of HIF-1αof IPC group was significantly higher than that of sham-operation group on the 1^st, 3^rd and 7^th days after reperfusion respectively （125.93±3.79 vs 117.65±5.60, 140.63±4.64 vs 119.33±4.26, 131.15±2.74 vs 107.60±3.89, t=2.449, 6.763,9.899,P 〈 0.05-0.01）. The expression of EPO of IPC group was significantly higher than that of sham-operation group on the 3^rd and 7^th days after perfusion respectively （141.68±3.29 vs 126.33±4.51, 138.88±2.59 vs 125.58±6.18,t=5.499,3.970, P〈 0.05）. CONCLUSION ： ①IPC can protect the never cells in rat brain and the best time to onset of cerebral IT induced by IPC is 1 to 7 days after reperfusion. ② Neuroprotective effect of cerebral IT might be related to the expression of HIF-1α and its target gene EPO.展开更多
The involvement of apoptosis in mitochondrial toxin 3 nitropropionic acid (3 NPA) induced ischemic tolerance to transient focal cerebral ischemia in rats and the mechanism was investigated. 3 NPA at a dose of 20 m...The involvement of apoptosis in mitochondrial toxin 3 nitropropionic acid (3 NPA) induced ischemic tolerance to transient focal cerebral ischemia in rats and the mechanism was investigated. 3 NPA at a dose of 20 mg/kg or vehicle control was intraperitoneally into the rats. Three days later, rats were exposed to 2 h of middle cerebral artery occlusion followed by 24 h of reperfusion. Infarct volumes were assessed by 2,3,5 triphenyltetrazolinm chloride (TTC) staining 24 h after reperfusion. Neural cell apoptosis in cerebral ischemic penumbra was detected by terminal deoxynucleotidyl transferase mediated dUTP biotin in situ nick end labeling (TUNEL) and flow cytometry methods (FCM). The results showed that as compared to the vehicle treated group, pretreatment with 3 NPA could reduce the infarct volume by 23.3 % and decrease the number of TUNEL positive neural cells and apoptotic percentage by 47 % ( P< 0.05) and 44.9 % ( P< 0 01), respectively. It was concluded that the development of 3 NPA induced ischemic tolerance in brain might be related to the decreases in neural cell apoptosis.展开更多
BACKGROUND： Numerous studies have shown that transient ischemic preconditioning induces cerebral ischemic tolerance. However, the underlying mechanisms of endogenous protection following ischemic preconditioning rema...BACKGROUND： Numerous studies have shown that transient ischemic preconditioning induces cerebral ischemic tolerance. However, the underlying mechanisms of endogenous protection following ischemic preconditioning remain unclear. OBJECTIVE： To dynamically measure erythropoietin and hypoxia-inducible factor-1α （HIF-1α） mRNA and protein expression at various times following preconditioning, and to investigate effects of erythropoietin and HIF-1α on cerebral ischemic tolerance in a model of focal ischemia/reperfusion established using the twice suture method. DESIGN, TIME AND SETTING： The randomized, controlled study was performed at the Institute of Anatomy, Medical College, Qingdao University, China from March 2006 to March 2007. MATERIALS： Rabbit anti-rat HIF-1α monoclonal antibody and biotinylated goat anti-rabbit IgG （Boster, China）, rabbit anti-rat erythropoietin monoclonal antibody （Santa Cruz Biotechnology, USA）, and one-step RT-PCR kit （Qiagen, Germany） were used in this study. METHODS： A total of 99 healthy, male, Wistar rats were randomly assigned to three groups： sham surgery （n = 9）, non-ischemic preconditioning （n = 45）, and ischemic preconditioning （n = 45）. In the ischemic preconditioning group, rat models of pre-ischemia-reperfusion-ischemia-reperfusion were established by occluding the left middle cerebral artery using the twice suture method. In the non-ischemic preconditioning group, pre-ischemia was replaced by sham surgery. Subsequently, the ischemic preconditioning and non-ischemic preconditioning groups were equally divided into five subgroups according to time of first reperfusion, including 1-, 3-, 7-, 14-, and 21-day subgroups. The sham surgery group received the sham surgery twice. MAIN OUTCOME MEASURES： HIF-la and erythropoietin protein expression was measured in the cerebral cortex, corpus striatum, and hippocampus of the ischemic hemisphere. HIF-1α and erythropoietin mRNA expression were determined in the frontal and parietal cortex of the ischemic hemisphere. RESULTS： （1） Intergroup comparison： compared with the non-ischemic preconditioning group, HIF-1α protein expression significantly increased in the rat cerebral cortex, corpus striatum, and hippocampus in the ischemic hemisphere at 1,3, and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05 or P 〈 0.01）. Erythropoietin protein expression significantly increased in the cerebral cortex, corpus striatum, and hippocampus, as well as HIF-1α and erythropoietin mRNA expression in the frontal and parietal cortex in the ischemic hemisphere, at 3 and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05）. （2） Temporal expression： HIF-1α protein expression in the rat cerebral cortex, corpus striatum, and hippocampus, as well as HIF-la mRNA expression in the frontal and parietal cortex, in the ischemic hemisphere increased at 3 days, and gradually decreased from 7 days following reperfusion in the ischemic preconditioning group. Temporal erythropoietin protein and mRNA expression was consistent with HIF-1α protein expression. （3） Correlation： erythropoietin mRNA expression positively correlated with HIF-1α mRNA expression （r= 0.737, P 〈 0.01）. CONCLUSION： Ischemic preconditioning induced cerebral ischemic tolerance. Pre-ischemiainduced increase in endogenous HIF-1αexpression, as well as its target gene erythropoietin, participated in the formation of cerebral ischemic tolerance.展开更多
Objective To determine the length of warm ischemic ( WI) tolerance in bronchial graft from non - heart - beating donors. Methods Forty - eight rats were randomly divided into 4 groups ( each group having 12 rats) acco...Objective To determine the length of warm ischemic ( WI) tolerance in bronchial graft from non - heart - beating donors. Methods Forty - eight rats were randomly divided into 4 groups ( each group having 12 rats) according to different WI durations including WI - 0 min ( group A) ,WI - 30 min ( group B) ,WI - 45展开更多
Background Preconditioning with repeated electroacupuncture （EA） could mimic ischemic preconditioning to induce cerebral ischemic tolerance in rats. The present study was designed to investigate whether mu（μ）-, d...Background Preconditioning with repeated electroacupuncture （EA） could mimic ischemic preconditioning to induce cerebral ischemic tolerance in rats. The present study was designed to investigate whether mu（μ）-, delta（δ）- or kappa（κ）-opioid receptors are involved in the neuroprotecUon induced by repeated EA preconditioning. Methods The rats were pretreated with naltrindole （NTI）, nor-binaltorphimine （nor-BNI） or D-Phe-Cys-Tyr-D- Trp-Om-Thr-Pen-Thr-NH2 （CTOP）, which is a highly selective δ-, κ- or μ-opioid receptor antagonist respectively, before each EA preconditioning （30 minutes per day, 5 days）. Twenty-four hours after the last EA treatment, the middle cerebral artery occlusion （MCAO） was induced for 120 minutes. The brain infarct volume was determined with 2,3,5-tdphenyltetrazolium chloride staining at 24 hours after MCAO and compared with that in rats which only received EA preconditioning. In another experiment, the met-enkephalin-like immunoreactivity in rat brain was investigated by immunohistochemistry in both EA preconditioning and control rats. Results The EA preconditioning reduced brain infarct volume compared with the control rats （P=-0.000）. Administration of both NTI and CTOP attenuated the brain infarct volume reduction induced by EA preconditioning, presenting with larger infarct volume than that in the EA preconditioning rats （P〈0.001）. But nor-BNI administration did not block the infarct volume reduction induced by EA preconditioning, presenting with smaller infarct volume than the control group rats （P=-0.000）. The number of met-enkephalin-like immunoreactivity positive neurons in the EA preconditioning rats was more than that of the control rats （P=-0.000）. Conclusion Repeated EA preconditioning stimulates the release of enkephalins, which may bind 5- and p-opioid receptors to induce the tolerance against focal cerebral ischemia.展开更多
In this study, we hypothesized that an increase in integrin αβand its co-activator vascular endothelial growth factor play important neuroprotective roles in ischemic injury. We performed ischemic preconditioning wi...In this study, we hypothesized that an increase in integrin αβand its co-activator vascular endothelial growth factor play important neuroprotective roles in ischemic injury. We performed ischemic preconditioning with bilateral common carotid artery occlusion for 5 minutes in C57BL/6J mice. This was followed by ischemic injury with bilateral common carotid artery occlusion for 30 minutes. The time interval between ischemic preconditioning and lethal ischemia was 48 hours. Histopathological analysis showed that ischemic preconditioning substantially diminished damage to neurons in the hippocampus 7 days after ischemia. Evans Blue dye assay showed that ischemic preconditioning reduced damage to the blood-brain barrier 24 hours after ischemia. This demonstrates the neuroprotective effect of ischemic preconditioning. Western blot assay revealed a significant reduction in protein levels of integrin αβ, vascular endothelial growth factor and its receptor in mice given ischemic preconditioning compared with mice not given ischemic preconditioning 24 hours after ischemia. These findings suggest that the neuroprotective effect of ischemic preconditioning is associated with lower integrin αβand vascular endothelial growth factor levels in the brain following ischemia.展开更多
Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain isch...Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method.After 2 hours of ischemia,the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds.This procedure was repeated six times.Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia,and up-regulate acid-sensing ion channel 2a expression at the m RNA and protein level.These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia,which promotes neuronal tolerance to ischemic brain injury.展开更多
Previous studies of integrin αvβ3 have focused on ischemic brain damage, although the role of integrin αvβ3 in ischemic preconditioning （IP） has rarely been reported. The present study analyzed the effects of IP...Previous studies of integrin αvβ3 have focused on ischemic brain damage, although the role of integrin αvβ3 in ischemic preconditioning （IP） has rarely been reported. The present study analyzed the effects of IP on integrin αvβ3 mRNA expression following cerebral ischemia through the use of hematoxylin-eosin staining and real-time quantitative polymerase chain reaction techniques. Integrin avid3 mRNA expression in the ischemia group peaked at 24 hours after ischemia-reperfusion. In the IP ＋ ischemia group, integrin αvβ3 mRNA expression increased after 24 hours, but remained significantly less than the ischemia group, and expression continued to increase until 7 days after ischemiaJreperfusion. These results demonstrate that IP effectively attenuated upregulation of integrin αvβ3 mRNA expression at 24 hours after ischemia.展开更多
Summary： To systematically evaluate the importance of protein synthesis in ischemic preconditioning （PC）-induced ischemic tolerance （IT）, temporary middle cerebral artery occlusion （MCAO） by Longa （20 min） wa...Summary： To systematically evaluate the importance of protein synthesis in ischemic preconditioning （PC）-induced ischemic tolerance （IT）, temporary middle cerebral artery occlusion （MCAO） by Longa （20 min） was used for PC （ischemic precondioning）. Twenty-four hours of reperfusion was allowed after PC and before permanent MCAO to establish ischemic tolerance （IT） to compare with non-PC （sham-operated） rats （n=5 for each group）. Infarct size and neurological deficits were measured 24 h after PMCAO. Samples of brain were taken for the determination of HSP70 expression by Western blot analysis. The effects of the protein synthesis inhibitor cycloheximide administered just before PC or administered long after PC but just before PMCAO on IT were also determined （n=5 for each group）. Our results showed that hemispheric infarct was significantly reduced （P〈0.01） only if PC was performed after 24 h, and PC significantly （P〈0.05） reduced neurological deficits （similar to reductions in infarct size）. Cycloheximide eliminated ischemic PC-induced IT effects on both brain injury and neurological deficits if administered before PC but not if administered long after PC but before PMCAO. PC produced no brain injury but did increase HSP70 protein 24 h after PC. Cycloheximide eliminated that effect. The results suggest that PC is a powerful inducer of ischemic brain tolerance as reflected by the preservation of brain tissue and motor function. PC induces IT that is dependent on de novo protein synthesis.展开更多
The astrocyte is a critical regulator of neuronal survival after ischemic brain injury. Electroacupuncture may be an effective therapy for cerebral ischemia, as electroacupuncture frequency can affect the structural i...The astrocyte is a critical regulator of neuronal survival after ischemic brain injury. Electroacupuncture may be an effective therapy for cerebral ischemia, as electroacupuncture frequency can affect the structural integdty of astrocytes. In this study, a rat model of middle cerebral artery occlusion established using the modified thread embolism method was treated with electroacupuncture of the bilateral Quchi （Llll） and Zusanfi （ST36） at 15, 30, and 100 Hz frequencies. Behavioral testing, immunohistochemistry and electron microscopy were used to explore the effect of these electroacupuncture frequencies used on maintaining the structural integrity of ischemic brain tissue. Compared with the model and 100 Hz electroacupuncture groups the 15 and 30 Hz electroacupuncture groups displayed decreased neurological deficit scores, as evaluated by the ＂Longa＂ method, significantly increased glial fibrillary acidic protein expression, and alleviated ultrastructural damage of astrocytes at the edge of the infarct. Our experimental findings indicate that 15 and 30 Hz electroacupuncture intervention can favorably maintain the structural integrity of astrocytes and play a protective role in cerebral ischemic injury. Astrocyte structural integrity may be the mechanism underlying acupuncture production of ischemic tolerance展开更多
Cortical spreading depression is a technique used to depolarize neurons. During focal or global ischemia, cortical spreading depression-induced preconditioning can enhance tolerance of further injury. However, the und...Cortical spreading depression is a technique used to depolarize neurons. During focal or global ischemia, cortical spreading depression-induced preconditioning can enhance tolerance of further injury. However, the underlying mechanism for this phenomenon remains relatively unclear. To date, numerous issues exist regarding the experimental model used to precondition the brain with cortical spreading depression, such as the administration route, concentration of potassium chloride, induction time, duration of the protection provided by the treatment, the regional distribution of the protective effect, and the types of neurons responsible for the greater tolerance. In this review, we focus on the mechanisms underlying cor- tical spreading depression-induced tolerance in the brain, considering excitatory neurotransmission and metabolism, nitric oxide, genomic reprogramming, inflammation, neurotropic factors, and cellular stress response. Specifically, we clarify the procedures and detailed information regarding cortical spreading depression-induced preconditioning and build a foundation for more comprehensive investigations in the field of neural regeneration and clinical application in the future.展开更多
Hypoxia-inducible factor 1 （HIF-1） can lead to the adaptative reaction of body for hypoxia and ischemia. HIF-1 plays an important role in the response of ischemia-hypoxia. At present, there has been no overall repor...Hypoxia-inducible factor 1 （HIF-1） can lead to the adaptative reaction of body for hypoxia and ischemia. HIF-1 plays an important role in the response of ischemia-hypoxia. At present, there has been no overall report on the significance for the expression of HIF-1 following experimental cerebral ischemia. OBJECTIVE： To observe the expression of HIF-1 after middle cerebral artery occlusion （MCAO） by immunohistochemical method. DESIGN： Completely randomly grouped controlled animal experiment. SETTING： Second Hospital, Xi＇an Jiaotong University. MATERIALS： Thirty-six Sprague-Dawley healthy male rats, with body mass of 250 - 330 g, were used in this study. Thirty-six rats were randomized into 3 groups： preischemia group, sham-operation group and control group, with 12 rats in each. METHODS： This study was carried out in the clinical laboratory, People＇s Hospital of Ningjin County of Shandong Province from March 2006 to January 2007. Rats in the pre-ischemia group were created into preischemia models by two embolisms twice. Three days after ischemic preconditioning, middle cerebral artery （MCA） was occluded for 2 hours with the same method. After being perfused for 22 hours, the rats were euthanized. In the sham-operation group, rats were not given the treatment of preischemia. In the first operation, only common carotid artery （CCA） and its crotch were exposed in the first operation, and MCA was not blocked by inserting embolism. At postoperative 3 days, rats were euthanized after being subjected to MCAO for 2 hours and reperfusion 22 hours by the same procedure as that in the preischemia group. As for each rat in the control group, only CCA and its crotch were exposed, and no any other treatment was carried out on them. MAIN OUTCOME MEASURES： Brain tissue of each rat was performed immunohistochemical staining at reperfusion 22 hours after preischemia, HIF-1 expression and brain infarct volume were detected. RESULTS： Thirty-six Sprague-Dawley rats were involved in the experiment. During the experiment, 8 rats dropped out, and another 8 rats were supplemented. The infarct volume of rats in the preischemia group was significantly smaller than that in the sham-operation group （t=3.22, P 〈 0.01 ） . HIF-1 expression was not found in the control group, but many HIF-I positive cells were found in the other two groups. Absorbance in the preischemia group was significantly higher than that in the sham-operation group （t=4.31, P 〈 0.01）. CONCLUSION： Slight ischemia caused preconditioning can increase HIF-1 content, and it is one of protective mechanisms for nerve cells.展开更多
This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia Methods Sixty male SD rats were used in this study Thirty animals underw...This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia Methods Sixty male SD rats were used in this study Thirty animals underwent transient middle cerebral artery occlusion (MCAO) and the other thirty permanent MCAO model The rats were randomly allocated to 3 sub-groups: control group (n=10), HBO-3 group (n=10), and HBO-5 group (n=10) The animals in HBO-3 and HBO-5 groups received 1*!hour hyperbaric oxygenation at 2 5 atmosphere absolute (ATA) in 100% oxygen every day for 3 and 5 days, respectively The animals in the control group received sham treatments 24*!hours after the last HBO, transient MCAO (120 min) and permanent MCAO were induced by introducing a 3-0 nylon monofilament suture through internal carotid artery based on the Koizumi technique The neurological outcome was evaluated until 24*!hours after reperfusion in transient MCAO rats and ischemia in permanent MCAO rats The infarct volume was then assessed by TTC staining Results In transient MCAO rats, the neurological outcome in both the HBO-3 and HBO-5 groups was better than that of the control group ( P <0 05 and 0 001) The infarct volume decreased from 171 5±113*!mm 3 to 40 6±49 9*!mm 3 ( P <0 05) in the HBO-3 group and 16 2±28 8*!mm 3 ( P <0 01) in the HBO-5 group There were no significant differences in neurological outcome and infarct volume among the three groups in permanent MCAO rats Conclusions The present study demonstrated that HBO preconditioning can induce ischemic tolerance in transient not permanent MCAO rats in a “dose-dependent' manner展开更多
Objective:To investigate,in basal ganglia,the factors associated with early neurological deterioration(END)of isolated acute lacunar infarction.Methods:167 patients,in the retrospective group,with isolated acute lacun...Objective:To investigate,in basal ganglia,the factors associated with early neurological deterioration(END)of isolated acute lacunar infarction.Methods:167 patients,in the retrospective group,with isolated acute lacunar infarction in basal ganglia,were defined by magnetic resonance imaging(MRI).The National Institutes of Health Stroke Scale(NIHSS)defined early neurological deterioration as increases of≥2 within 72 hours following admission.Baseline variables predicting END were investigated with multivariate logistic regression analysis.Results:In the study,END occurred in 42(25.15%)patients.Lesions located in posterior limb of internal capsule were independent risk factors for END(P<0.01).Associated with END were the age of onset,history of cerebral infarction,history of diabetes,systolic blood pressure at admission and lesions of cerebral white matter.This presented significant differences(P<0.05).With or without diabetes and different lesion location at varying layers and inter-layers,single-factor and multi-factor analysis revealed no effect on the association between positive ENT and age,history of stroke,white matter.Previous history of stroke,pathological changes of white matter,and age of onset,correlates with END which showed significant difference(P<0.05).Conclusions:There is a close relationship between the lesion location and other related factors,such as lesions of cerebral white matter,history of cerebral infarction,history of diabetes and age,etc.and END in patients with isolated acute lacunar infarction in basal ganglia.Protective factors of END included age≥65,high systolic pressure,stroke history,cerebral white matter lesions in our study.展开更多
文摘Diabetic retinopathy is a leading cause of acquired blindness, and it is the most common ischemic disorder of the retina. Available treatments are not very effective. Efforts to inhibit diabetic reti- nopathy have focused either on highly specific therapeutic approaches for pharmacologic targets or using genetic approaches to change expression of certain enzymes. However, it might be wise to choose innovative treatment modalities that act by multiple potential mechanisms. The resis- tance to ischemic injury, or ischemic tolerance, can be transiently induced by prior exposure to a non-injurious preconditioning stimulus. A complete functional and histologic protection against retinal ischemic damage can be achieved by previous preconditioning with non-damaging isch- emia. In this review, we will discuss evidence that supports that ischemic conditioning could help avert the dreaded consequences that results from retinal diabetic damage.
基金the Scientific andTechnological DevelopmentProgram of Qingdao City, No.No.05-1-NS-73
文摘BACKGROUND： Hypoxia inducible factor-1 alpha （HIF-1 （x） and erythropoietin（EPO）, possessing neuroprotective effect in the cerebral ischemia, might play an important role in the formation of cerebral ischemic tolerance （IT）. OBJECTIVE：To observe the neuroprotective effect of cerebral ischemic preconditioning（IPC） of rats, and the expression and mechanism of HIF-1α and target gene erythropoietin in the brain tissue following the formation of cerebral IT. DESIGN ： A randomized and controlled observation SETTING： Department of Neurology, the Affiliated Hospital of Medical College, Qingdao University MATERIALS： Totally 84 enrolled adult healthy male Wistar rats of clean grade, weighing 250 to 300 g, were provided by the Animal Experimental Department, Tongji Medical College of Huazhong University of Science and Technology. Ready-to-use SABC reagent kit and rabbit anti-rat HIF-1α monoclonal antibody were purchased from Boshide Bioengineering Co.Ltd （Wuhan）; Rabbit anti-rat EPO monoclonal antibody was purchased from Santa Cruz Company （USA）. METHODS： This experiment was carried out in the Department of Anatomy, Medical College, Qingdao University during March 2005 to March 2006. ① The 84 rats were divided into 3 groups by a lot： IPC group （n=40）, sham-operation group （n=40） and control group （n=4）. In the IPC group, middle cerebral artery was occluded for 2 hours respectively on the 1^st, 3^rd, 7^th, 14^th and 21^st days of the reperfusion following 10-minute preischemia was made using a modified middle cerebral artery second suture method from Zea-Longa. The rats were sacrificed 22 hours after reperfusion in the end of middle cerebral artery occlusion （MCAO）. That was to say, after 10-minute preischemia, suture was exited to the extemal carotid artery and embedded subcutaneously. Middle cerebral artery was occluded again to form the second reperfusion at the set time point after reperfusion. Twenty-two hours later, rats were sacrificed; In the sham-operation group,the preischemia was substituted by sham-operation（only common carotid artery and crotch were exposed, and MCAO by suture was omitted）, and the other procedures were the same as those in the IPC group. In the control group, rats were given sham-operation twice at an interval of one day, and they were sacrificed 24 hours after the second sham-operation. ② Brain tissue was taken from the rats in each group. Cerebral infarction area of each layer was measured with TTC staining, and total cerebral infarction volume （The total cerebral infarction area of each layerxinterspace ） was calculated. After brain tissue was stained by haematoxylin-esoin （HE）, the form of nerve cells was observed under an optical microscope, and the expressions of HIF-1α（and EPO protein in the brain tissue were detected with immunohistochemical method. MAIN OUTCOME MEASURES： ①Cerebral infarction volume;②form of nerve cell; ③ the expression of HIF-1α and EPO protein in the brain tissue. RESULTS：Totally 84 rats were enrolled in the experiment. The dead rats were randomly supplied during the experiment, and finally 84 rats entered the stage of result analysis. ① Detection of cerebral infarction volume of rats in each group： Cerebral infarction volume in the IPC group was significantly smaller than that in the sham-operation group on the 1^st, 3^rd and 7^th days after reperfusion respectively [（161.2±6.9） mm^3 vs （219.9±11.2） mm^3, （134.9±9.0） mm^3 vs （218.6±13.0） mm^3, （142.9±13.7） mm^3 vs （221.3±14.2） mm^3, t=-8.924, 10.587,7.947, P〈 0.01]. ② Observation of nerve cell form of brain tissue： HE staining showed that the ischemic degree, range and cerebral edema degree of IPC group were significantly milder than those of sham-operation group. ③ The expressions of HIF-1α and EPO protein in cerebral cortex and hippocampus ： The expression of HIF-1αof IPC group was significantly higher than that of sham-operation group on the 1^st, 3^rd and 7^th days after reperfusion respectively （125.93±3.79 vs 117.65±5.60, 140.63±4.64 vs 119.33±4.26, 131.15±2.74 vs 107.60±3.89, t=2.449, 6.763,9.899,P 〈 0.05-0.01）. The expression of EPO of IPC group was significantly higher than that of sham-operation group on the 3^rd and 7^th days after perfusion respectively （141.68±3.29 vs 126.33±4.51, 138.88±2.59 vs 125.58±6.18,t=5.499,3.970, P〈 0.05）. CONCLUSION ： ①IPC can protect the never cells in rat brain and the best time to onset of cerebral IT induced by IPC is 1 to 7 days after reperfusion. ② Neuroprotective effect of cerebral IT might be related to the expression of HIF-1α and its target gene EPO.
基金ThisprojectwassupportedbyagrantfrominitiativeFoundationofNatioualEducationMinistryforscholarscomingbackfromothercountries (No .2 0 0 1 345)
文摘The involvement of apoptosis in mitochondrial toxin 3 nitropropionic acid (3 NPA) induced ischemic tolerance to transient focal cerebral ischemia in rats and the mechanism was investigated. 3 NPA at a dose of 20 mg/kg or vehicle control was intraperitoneally into the rats. Three days later, rats were exposed to 2 h of middle cerebral artery occlusion followed by 24 h of reperfusion. Infarct volumes were assessed by 2,3,5 triphenyltetrazolinm chloride (TTC) staining 24 h after reperfusion. Neural cell apoptosis in cerebral ischemic penumbra was detected by terminal deoxynucleotidyl transferase mediated dUTP biotin in situ nick end labeling (TUNEL) and flow cytometry methods (FCM). The results showed that as compared to the vehicle treated group, pretreatment with 3 NPA could reduce the infarct volume by 23.3 % and decrease the number of TUNEL positive neural cells and apoptotic percentage by 47 % ( P< 0.05) and 44.9 % ( P< 0 01), respectively. It was concluded that the development of 3 NPA induced ischemic tolerance in brain might be related to the decreases in neural cell apoptosis.
基金the Scientific and Technological Development Program of Qingdao City, No.05-1-NS-73
文摘BACKGROUND： Numerous studies have shown that transient ischemic preconditioning induces cerebral ischemic tolerance. However, the underlying mechanisms of endogenous protection following ischemic preconditioning remain unclear. OBJECTIVE： To dynamically measure erythropoietin and hypoxia-inducible factor-1α （HIF-1α） mRNA and protein expression at various times following preconditioning, and to investigate effects of erythropoietin and HIF-1α on cerebral ischemic tolerance in a model of focal ischemia/reperfusion established using the twice suture method. DESIGN, TIME AND SETTING： The randomized, controlled study was performed at the Institute of Anatomy, Medical College, Qingdao University, China from March 2006 to March 2007. MATERIALS： Rabbit anti-rat HIF-1α monoclonal antibody and biotinylated goat anti-rabbit IgG （Boster, China）, rabbit anti-rat erythropoietin monoclonal antibody （Santa Cruz Biotechnology, USA）, and one-step RT-PCR kit （Qiagen, Germany） were used in this study. METHODS： A total of 99 healthy, male, Wistar rats were randomly assigned to three groups： sham surgery （n = 9）, non-ischemic preconditioning （n = 45）, and ischemic preconditioning （n = 45）. In the ischemic preconditioning group, rat models of pre-ischemia-reperfusion-ischemia-reperfusion were established by occluding the left middle cerebral artery using the twice suture method. In the non-ischemic preconditioning group, pre-ischemia was replaced by sham surgery. Subsequently, the ischemic preconditioning and non-ischemic preconditioning groups were equally divided into five subgroups according to time of first reperfusion, including 1-, 3-, 7-, 14-, and 21-day subgroups. The sham surgery group received the sham surgery twice. MAIN OUTCOME MEASURES： HIF-la and erythropoietin protein expression was measured in the cerebral cortex, corpus striatum, and hippocampus of the ischemic hemisphere. HIF-1α and erythropoietin mRNA expression were determined in the frontal and parietal cortex of the ischemic hemisphere. RESULTS： （1） Intergroup comparison： compared with the non-ischemic preconditioning group, HIF-1α protein expression significantly increased in the rat cerebral cortex, corpus striatum, and hippocampus in the ischemic hemisphere at 1,3, and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05 or P 〈 0.01）. Erythropoietin protein expression significantly increased in the cerebral cortex, corpus striatum, and hippocampus, as well as HIF-1α and erythropoietin mRNA expression in the frontal and parietal cortex in the ischemic hemisphere, at 3 and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05）. （2） Temporal expression： HIF-1α protein expression in the rat cerebral cortex, corpus striatum, and hippocampus, as well as HIF-la mRNA expression in the frontal and parietal cortex, in the ischemic hemisphere increased at 3 days, and gradually decreased from 7 days following reperfusion in the ischemic preconditioning group. Temporal erythropoietin protein and mRNA expression was consistent with HIF-1α protein expression. （3） Correlation： erythropoietin mRNA expression positively correlated with HIF-1α mRNA expression （r= 0.737, P 〈 0.01）. CONCLUSION： Ischemic preconditioning induced cerebral ischemic tolerance. Pre-ischemiainduced increase in endogenous HIF-1αexpression, as well as its target gene erythropoietin, participated in the formation of cerebral ischemic tolerance.
文摘Objective To determine the length of warm ischemic ( WI) tolerance in bronchial graft from non - heart - beating donors. Methods Forty - eight rats were randomly divided into 4 groups ( each group having 12 rats) according to different WI durations including WI - 0 min ( group A) ,WI - 30 min ( group B) ,WI - 45
基金the National Natural Science Foundation of China(No.30471664).
文摘Background Preconditioning with repeated electroacupuncture （EA） could mimic ischemic preconditioning to induce cerebral ischemic tolerance in rats. The present study was designed to investigate whether mu（μ）-, delta（δ）- or kappa（κ）-opioid receptors are involved in the neuroprotecUon induced by repeated EA preconditioning. Methods The rats were pretreated with naltrindole （NTI）, nor-binaltorphimine （nor-BNI） or D-Phe-Cys-Tyr-D- Trp-Om-Thr-Pen-Thr-NH2 （CTOP）, which is a highly selective δ-, κ- or μ-opioid receptor antagonist respectively, before each EA preconditioning （30 minutes per day, 5 days）. Twenty-four hours after the last EA treatment, the middle cerebral artery occlusion （MCAO） was induced for 120 minutes. The brain infarct volume was determined with 2,3,5-tdphenyltetrazolium chloride staining at 24 hours after MCAO and compared with that in rats which only received EA preconditioning. In another experiment, the met-enkephalin-like immunoreactivity in rat brain was investigated by immunohistochemistry in both EA preconditioning and control rats. Results The EA preconditioning reduced brain infarct volume compared with the control rats （P=-0.000）. Administration of both NTI and CTOP attenuated the brain infarct volume reduction induced by EA preconditioning, presenting with larger infarct volume than that in the EA preconditioning rats （P〈0.001）. But nor-BNI administration did not block the infarct volume reduction induced by EA preconditioning, presenting with smaller infarct volume than the control group rats （P=-0.000）. The number of met-enkephalin-like immunoreactivity positive neurons in the EA preconditioning rats was more than that of the control rats （P=-0.000）. Conclusion Repeated EA preconditioning stimulates the release of enkephalins, which may bind 5- and p-opioid receptors to induce the tolerance against focal cerebral ischemia.
基金supported by grants from the National Natural Science Foundation of China,No.81071068the Israel Science Foundation-the National Natural Science Foundation of China(Joint Program),No.813111290the Natural Science Foundation of Guangdong Province in China,No.2014A030313172
文摘In this study, we hypothesized that an increase in integrin αβand its co-activator vascular endothelial growth factor play important neuroprotective roles in ischemic injury. We performed ischemic preconditioning with bilateral common carotid artery occlusion for 5 minutes in C57BL/6J mice. This was followed by ischemic injury with bilateral common carotid artery occlusion for 30 minutes. The time interval between ischemic preconditioning and lethal ischemia was 48 hours. Histopathological analysis showed that ischemic preconditioning substantially diminished damage to neurons in the hippocampus 7 days after ischemia. Evans Blue dye assay showed that ischemic preconditioning reduced damage to the blood-brain barrier 24 hours after ischemia. This demonstrates the neuroprotective effect of ischemic preconditioning. Western blot assay revealed a significant reduction in protein levels of integrin αβ, vascular endothelial growth factor and its receptor in mice given ischemic preconditioning compared with mice not given ischemic preconditioning 24 hours after ischemia. These findings suggest that the neuroprotective effect of ischemic preconditioning is associated with lower integrin αβand vascular endothelial growth factor levels in the brain following ischemia.
文摘Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method.After 2 hours of ischemia,the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds.This procedure was repeated six times.Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia,and up-regulate acid-sensing ion channel 2a expression at the m RNA and protein level.These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia,which promotes neuronal tolerance to ischemic brain injury.
基金the National Natural Science Foundation of China,No. 30870849,81071068the Science and Technology Planning Project of Guangdong Province,No. 2009B030801101
文摘Previous studies of integrin αvβ3 have focused on ischemic brain damage, although the role of integrin αvβ3 in ischemic preconditioning （IP） has rarely been reported. The present study analyzed the effects of IP on integrin αvβ3 mRNA expression following cerebral ischemia through the use of hematoxylin-eosin staining and real-time quantitative polymerase chain reaction techniques. Integrin avid3 mRNA expression in the ischemia group peaked at 24 hours after ischemia-reperfusion. In the IP ＋ ischemia group, integrin αvβ3 mRNA expression increased after 24 hours, but remained significantly less than the ischemia group, and expression continued to increase until 7 days after ischemiaJreperfusion. These results demonstrate that IP effectively attenuated upregulation of integrin αvβ3 mRNA expression at 24 hours after ischemia.
文摘Summary： To systematically evaluate the importance of protein synthesis in ischemic preconditioning （PC）-induced ischemic tolerance （IT）, temporary middle cerebral artery occlusion （MCAO） by Longa （20 min） was used for PC （ischemic precondioning）. Twenty-four hours of reperfusion was allowed after PC and before permanent MCAO to establish ischemic tolerance （IT） to compare with non-PC （sham-operated） rats （n=5 for each group）. Infarct size and neurological deficits were measured 24 h after PMCAO. Samples of brain were taken for the determination of HSP70 expression by Western blot analysis. The effects of the protein synthesis inhibitor cycloheximide administered just before PC or administered long after PC but just before PMCAO on IT were also determined （n=5 for each group）. Our results showed that hemispheric infarct was significantly reduced （P〈0.01） only if PC was performed after 24 h, and PC significantly （P〈0.05） reduced neurological deficits （similar to reductions in infarct size）. Cycloheximide eliminated ischemic PC-induced IT effects on both brain injury and neurological deficits if administered before PC but not if administered long after PC but before PMCAO. PC produced no brain injury but did increase HSP70 protein 24 h after PC. Cycloheximide eliminated that effect. The results suggest that PC is a powerful inducer of ischemic brain tolerance as reflected by the preservation of brain tissue and motor function. PC induces IT that is dependent on de novo protein synthesis.
基金supported by a grant from the Guangxi Administration of Traditional Chinese Medicine,No.GZZC0962
文摘The astrocyte is a critical regulator of neuronal survival after ischemic brain injury. Electroacupuncture may be an effective therapy for cerebral ischemia, as electroacupuncture frequency can affect the structural integdty of astrocytes. In this study, a rat model of middle cerebral artery occlusion established using the modified thread embolism method was treated with electroacupuncture of the bilateral Quchi （Llll） and Zusanfi （ST36） at 15, 30, and 100 Hz frequencies. Behavioral testing, immunohistochemistry and electron microscopy were used to explore the effect of these electroacupuncture frequencies used on maintaining the structural integrity of ischemic brain tissue. Compared with the model and 100 Hz electroacupuncture groups the 15 and 30 Hz electroacupuncture groups displayed decreased neurological deficit scores, as evaluated by the ＂Longa＂ method, significantly increased glial fibrillary acidic protein expression, and alleviated ultrastructural damage of astrocytes at the edge of the infarct. Our experimental findings indicate that 15 and 30 Hz electroacupuncture intervention can favorably maintain the structural integrity of astrocytes and play a protective role in cerebral ischemic injury. Astrocyte structural integrity may be the mechanism underlying acupuncture production of ischemic tolerance
基金supported by the National Natural Science Foundation of China,No.H0906-C090201a grant from the National Science and Technology Support Program of China,No.3G013F843428
文摘Cortical spreading depression is a technique used to depolarize neurons. During focal or global ischemia, cortical spreading depression-induced preconditioning can enhance tolerance of further injury. However, the underlying mechanism for this phenomenon remains relatively unclear. To date, numerous issues exist regarding the experimental model used to precondition the brain with cortical spreading depression, such as the administration route, concentration of potassium chloride, induction time, duration of the protection provided by the treatment, the regional distribution of the protective effect, and the types of neurons responsible for the greater tolerance. In this review, we focus on the mechanisms underlying cor- tical spreading depression-induced tolerance in the brain, considering excitatory neurotransmission and metabolism, nitric oxide, genomic reprogramming, inflammation, neurotropic factors, and cellular stress response. Specifically, we clarify the procedures and detailed information regarding cortical spreading depression-induced preconditioning and build a foundation for more comprehensive investigations in the field of neural regeneration and clinical application in the future.
文摘Hypoxia-inducible factor 1 （HIF-1） can lead to the adaptative reaction of body for hypoxia and ischemia. HIF-1 plays an important role in the response of ischemia-hypoxia. At present, there has been no overall report on the significance for the expression of HIF-1 following experimental cerebral ischemia. OBJECTIVE： To observe the expression of HIF-1 after middle cerebral artery occlusion （MCAO） by immunohistochemical method. DESIGN： Completely randomly grouped controlled animal experiment. SETTING： Second Hospital, Xi＇an Jiaotong University. MATERIALS： Thirty-six Sprague-Dawley healthy male rats, with body mass of 250 - 330 g, were used in this study. Thirty-six rats were randomized into 3 groups： preischemia group, sham-operation group and control group, with 12 rats in each. METHODS： This study was carried out in the clinical laboratory, People＇s Hospital of Ningjin County of Shandong Province from March 2006 to January 2007. Rats in the pre-ischemia group were created into preischemia models by two embolisms twice. Three days after ischemic preconditioning, middle cerebral artery （MCA） was occluded for 2 hours with the same method. After being perfused for 22 hours, the rats were euthanized. In the sham-operation group, rats were not given the treatment of preischemia. In the first operation, only common carotid artery （CCA） and its crotch were exposed in the first operation, and MCA was not blocked by inserting embolism. At postoperative 3 days, rats were euthanized after being subjected to MCAO for 2 hours and reperfusion 22 hours by the same procedure as that in the preischemia group. As for each rat in the control group, only CCA and its crotch were exposed, and no any other treatment was carried out on them. MAIN OUTCOME MEASURES： Brain tissue of each rat was performed immunohistochemical staining at reperfusion 22 hours after preischemia, HIF-1 expression and brain infarct volume were detected. RESULTS： Thirty-six Sprague-Dawley rats were involved in the experiment. During the experiment, 8 rats dropped out, and another 8 rats were supplemented. The infarct volume of rats in the preischemia group was significantly smaller than that in the sham-operation group （t=3.22, P 〈 0.01 ） . HIF-1 expression was not found in the control group, but many HIF-I positive cells were found in the other two groups. Absorbance in the preischemia group was significantly higher than that in the sham-operation group （t=4.31, P 〈 0.01）. CONCLUSION： Slight ischemia caused preconditioning can increase HIF-1 content, and it is one of protective mechanisms for nerve cells.
基金ThisstudywassupportedinpartbyagrantfromtheNationalNaturalScienceFoundationofChina (No 396 70 6 99)
文摘This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia Methods Sixty male SD rats were used in this study Thirty animals underwent transient middle cerebral artery occlusion (MCAO) and the other thirty permanent MCAO model The rats were randomly allocated to 3 sub-groups: control group (n=10), HBO-3 group (n=10), and HBO-5 group (n=10) The animals in HBO-3 and HBO-5 groups received 1*!hour hyperbaric oxygenation at 2 5 atmosphere absolute (ATA) in 100% oxygen every day for 3 and 5 days, respectively The animals in the control group received sham treatments 24*!hours after the last HBO, transient MCAO (120 min) and permanent MCAO were induced by introducing a 3-0 nylon monofilament suture through internal carotid artery based on the Koizumi technique The neurological outcome was evaluated until 24*!hours after reperfusion in transient MCAO rats and ischemia in permanent MCAO rats The infarct volume was then assessed by TTC staining Results In transient MCAO rats, the neurological outcome in both the HBO-3 and HBO-5 groups was better than that of the control group ( P <0 05 and 0 001) The infarct volume decreased from 171 5±113*!mm 3 to 40 6±49 9*!mm 3 ( P <0 05) in the HBO-3 group and 16 2±28 8*!mm 3 ( P <0 01) in the HBO-5 group There were no significant differences in neurological outcome and infarct volume among the three groups in permanent MCAO rats Conclusions The present study demonstrated that HBO preconditioning can induce ischemic tolerance in transient not permanent MCAO rats in a “dose-dependent' manner
文摘Objective:To investigate,in basal ganglia,the factors associated with early neurological deterioration(END)of isolated acute lacunar infarction.Methods:167 patients,in the retrospective group,with isolated acute lacunar infarction in basal ganglia,were defined by magnetic resonance imaging(MRI).The National Institutes of Health Stroke Scale(NIHSS)defined early neurological deterioration as increases of≥2 within 72 hours following admission.Baseline variables predicting END were investigated with multivariate logistic regression analysis.Results:In the study,END occurred in 42(25.15%)patients.Lesions located in posterior limb of internal capsule were independent risk factors for END(P<0.01).Associated with END were the age of onset,history of cerebral infarction,history of diabetes,systolic blood pressure at admission and lesions of cerebral white matter.This presented significant differences(P<0.05).With or without diabetes and different lesion location at varying layers and inter-layers,single-factor and multi-factor analysis revealed no effect on the association between positive ENT and age,history of stroke,white matter.Previous history of stroke,pathological changes of white matter,and age of onset,correlates with END which showed significant difference(P<0.05).Conclusions:There is a close relationship between the lesion location and other related factors,such as lesions of cerebral white matter,history of cerebral infarction,history of diabetes and age,etc.and END in patients with isolated acute lacunar infarction in basal ganglia.Protective factors of END included age≥65,high systolic pressure,stroke history,cerebral white matter lesions in our study.
