Endoplasmic reticulum stress and autophagy in cerebral ischemia/reperfusion injury:PERK as a potential target for intervention

Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cerebral ischemia,but the relationship between ER stress and autophagy remains unclear.In this study,we established experimental models using oxygen-glucose deprivation/reoxygenation in PC12 cells and primary neurons to simulate cerebral ischemia/reperfusion injury.We found that prolongation of oxygen-glucose deprivation activated the ER stress pathway protein kinase-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2 subunit alpha(e IF2α)-activating transcription factor 4(ATF4)-C/EBP homologous protein(CHOP),increased neuronal apoptosis,and induced autophagy.Furthermore,inhibition of ER stress using inhibitors or by si RNA knockdown of the PERK gene significantly attenuated excessive autophagy and neuronal apoptosis,indicating an interaction between autophagy and ER stress and suggesting PERK as an essential target for regulating autophagy.Blocking autophagy with chloroquine exacerbated ER stress-induced apoptosis,indicating that normal levels of autophagy play a protective role in neuronal injury following cerebral ischemia/reperfusion injury.Findings from this study indicate that cerebral ischemia/reperfusion injury can trigger neuronal ER stress and promote autophagy,and suggest that PERK is a possible target for inhibiting excessive autophagy in cerebral ischemia/reperfusion injury.

A matrix metalloproteinase-responsive hydrogel system controls angiogenic peptide release for repair of cerebral ischemia/reperfusion injury

Vascular endothelial growth factor and its mimic peptide KLTWQELYQLKYKGI(QK)are widely used as the most potent angiogenic factors for the treatment of multiple ischemic diseases.However,conventional topical drug delivery often results in a burst release of the drug,leading to transient retention(inefficacy)and undesirable diffusion(toxicity)in vivo.Therefore,a drug delivery system that responds to changes in the microenvironment of tissue regeneration and controls vascular endothelial growth factor release is crucial to improve the treatment of ischemic stroke.Matrix metalloproteinase-2(MMP-2)is gradually upregulated after cerebral ischemia.Herein,vascular endothelial growth factor mimic peptide QK was self-assembled with MMP-2-cleaved peptide PLGLAG(TIMP)and customizable peptide amphiphilic(PA)molecules to construct nanofiber hydrogel PA-TIMP-QK.PA-TIMP-QK was found to control the delivery of QK by MMP-2 upregulation after cerebral ischemia/reperfusion and had a similar biological activity with vascular endothelial growth factor in vitro.The results indicated that PA-TIMP-QK promoted neuronal survival,restored local blood circulation,reduced blood-brain barrier permeability,and restored motor function.These findings suggest that the self-assembling nanofiber hydrogel PA-TIMP-QK may provide an intelligent drug delivery system that responds to the microenvironment and promotes regeneration and repair after cerebral ischemia/reperfusion injury.

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.

Salvianolate increases heat shock protein expression in a cerebral ischemia-reperfusion injury model

Stroke remains a worldwide health problem. Salvianolate exerts a protective effect in various mi- crocirculatory disturbance-related diseases, but studies of the mechanisms underlying its protective action have mainly focused on the myocardium, whereas little research has been carried out in brain tissue following ischemia-reperfusion. We assessed the neuroprotective effects of salvianolate in a rat model of cerebral ischemia-reperfusion injury induced using the suture method. At onset and 24 and 48 hours after reperfusion, rats were intraperitoneally injected with salvianolate （18 mg/kg） or saline. Neurological deficit scores at 72 hours showed that the neurological functions of rats that had received salvianolate were significantly better than those of the rats that had received saline. 2,3,5-Triphenyltetrazolium chloride was used to stain cerebral tissue to determine the extent of the infarct area. A significantly smaller infarct area and a significantly lower number of apoptotic cells were observed after treatment with salvianolate compared with the saline treatment. Expression of heat shock protein 22 and phosphorylated protein kinase B in ischemic brain tissue was significantly greater in rats treated with salvianolate compared with rats treated with saline. Our findings suggest that salvianolate provides neuroprotective effects against cerebral ischemia-reperfusion injury by upregulating heat shock protein 22 and phosphorylated protein kinase B expression.

Acacetin protects against cerebral ischemia-reperfusion injury via the NLRP3 signaling pathway

Acacetin(5,7-dihydroxy-4′-methoxyflavone), a potential neuroprotective agent, has an inhibitory effect on lipopolysaccharide-induced neuroinflammatory reactions. However, whether acacetin has an effect on inflammatory corpuscle 3(NLRP3) after cerebral ischemia-reperfusion injury has not been fully determined. This study used an improved suture method to establish a cerebral ischemia-reperfusion injury model in C57BL/6 mice. After ischemia with middle cerebral artery occlusion for 1 hour, reperfusion with intraperitoneal injection of 25 mg/kg of acacetin(acacetin group) or an equal volume of saline(0.1 mL/10 g, middle cerebral artery occlusion group) was used to investigate the effect of acacetin on cerebral ischemia-reperfusion injury. Infarct volume and neurological function scores were determined by 2,3,5-triphenyltetrazolium chloride staining and the Zea-Longa scoring method. Compared with the middle cerebral artery occlusion group, neurological function scores and cerebral infarction volumes were significantly reduced in the acacetin group. To understand the effect of acacetin on microglia-mediated inflammatory response after cerebral ischemia-reperfusion injury, immunohistochemistry for the microglia marker calcium adapter protein ionized calcium-binding adaptor molecule 1(Iba1) was examined in the hippocampus of ischemic brain tissue. In addition, tumor necrosis factor-α, interleukin-1β, and interleukin-6 expression in ischemic brain tissue of mice was quantified by enzyme-linked immunosorbent assay. Expression of Iba1, tumor necrosis factor-α, interleukin-1β and interleukin-6 was significantly lower in the acacetin group compared with the middle cerebral artery occlusion group. Western blot assay results showed that expression of Toll-like receptor 4, nuclear factor kappa B, NLRP3, procaspase-1, caspase-1, pro-interleukin-1β, and interleukin-1β were significantly lower in the acacetin group compared with the middle cerebral artery occlusion group. Our findings indicate that acacetin has a protective effect on cerebral ischemia-reperfusion injury, and its mechanism of action is associated with inhibition of microglia-mediated inflammation and the NLRP3 signaling pathway.

Experimental Study on the Protection of Agrimony Extracts from Different Extracting Methods against Cerebral Ischemia-Reperfusion Injury

Objective To study the protective effect of agrimony extracts from different extracting methods on cerebral ischemia-reperfusion injury in rats, in order to optimize the extraction scheme of agrimony.Methods Male rats were randomly assigned into seven groups: 1. Sham-operated group, 2. Untreated MCAO group (MCAO), 3. Petroleum ether extract of Agrimonia pilosa treated MCAO group (PEA), 4. Ethyl acetate extract of Agrimonia pilosa treated MCAO group (EAEA), 5. Ethanol extract of Agrimonia pilosa treated MCAO group (EEA), 6. Water extract of Agrimonia pilosa treated MCAO group (WEA), 7. Nimodipine treated MCAO group (NP). Intragastrical drug administration (i.g) was performed at 0 and 6 hours after MCAO.Neurological function tests were performed after reperfusion for 24 hours, then the brain was removed for the evaluations of the cerebral infarction volume (percentage of total brain volume) by immunohistochemistry,histological changes (hematoxylin-eosin staining), Na+/K+-ATPase, Ca2+-ATPase (modified method of Svoboda and Mosinger), mRNA expression of Tumor suppressor gene (P53) and hot shock protein (HSP70)(quantitative real-time PCR).Results The neurological function of MCAO group had significantly higher scores than the sham group (P<0.01). The WEA group showed a significantly lower neurological score than the MCAO group (P<0.05),indicating the protective effect of WEA on neurological deficits. The mean infarction volumes of WEA (13.5±6.6%, F=4.75, P<0.01), EEA (19.90±6.90%, F=5.23, P<0.01), PEA (20.40±5.30%, F=4.68,P<0.01) and EAEA (22.50±10.50%, F=6.25, P<0.05) group were all significantly smaller than that of MCAO group (29.40±6.50%). HE staining demonstrated that, compared to the treated groups, the infarcted cerebral tissue of MCAO group had more swelling neural cells, lighter stained nucleus, fewer and irregularly distributed neurons. The activity of Na+/K+-ATPase and Ca2+-ATPase reduced in the MCAO group (3.67±0.48 U/mg,1.28±0.26 U/mg, respectively), and were significantly higher in WEA group (7.56±0.85 U/mg, F=12.65,P=0.010; 3.59±0.22 U/mg, F=8.32, P=0.041, respectively). The MCAO group showed significantly elevated P53 and HSP70 mRNA expressions compared to the sham group (P<0.01, P<0.05). P53 mRNA expressions in Agrimony extracts treated groups were significantly lower than that of the MCAO group (all P<0.01), with the WEA group showing the greatest difference from MCAO group. The HSP70 mRNA level of the treated groups were not significantly different from that of the MCAO group.Conclusions Treatment using water extracts of agrimony can promote the best functional and metabolic recovery for rat model of cerebral ischemia-reperfusion injury, which maybe relate with the upregulation of energy metabolism in nerve cells after MCAO.

Acupuncture effects on serum myelin basic protein and remyelination following 30 minutes and 2 hours of ischemia in a rat model of cerebral ischemia-reperfusion injury

BACKGROUND： Acupuncture treatment on injured cerebral axons has shown to provide efficacy in clinical practice. It is unknown whether acupuncture produces therapeutic effects by protecting injured cerebral myelin in ischemic stroke. OBJECTIVE： To test whether acupuncture provides protection for injured cerebral myelin, based on quantitative data from cerebral ischemia-reperfusion rats, and to compare the effects of early and late acupuncture on serum myelin basic protein （MBP） content and remyelination of the ischemic internal capsule.DESIGN, TIME AND SETTING： A randomized, controlled experiment was performed at the Neurobiological Laboratory, Sichuan University from March 2005 to March 2006. MATERIALS： ＂Hua Tuo＂ Brand filiform needles were produced by the Medical Instrument Factory of Suzhou, China.METHODS： A total of 52 adult, healthy, male, Sprague Dawley rats were randomly assigned to four groups： control （n = 4）, model （n = 16）, early acupuncture （n = 16）, and late acupuncture （n = 16）. The focal cerebral ischemia-reperfusion model was established by middle cerebral artery occlusion in the right hemisphere using the modified thread embolism method in the latter three groups. Early and late acupuncture groups underwent acupuncture after ischemia for 30 minutes and 2 hours using the Xingnaokaiqiao needling method, respectively. Acupoints were ＂Neiguarf＇ （PC 6） and ＂Sanyinjiao＂ （SP 6） on the bilateral sides, as well as ＂Shuigou＇ （DU 26） and ＂Baihui＂ （DU 20） with stimulation for 1 minute at each acupoint. Acupuncture at all acupoints was performed two or three times while the needle was retained, once per day. No special handling was administered to the control clroup.MAIN OUTCOME MEASURES： For each group, remyelination of the internal capsule was observed by Pal-Weigert＇s myelin staining and serum MBP content was detected using enzyme-linked immunosorbent assay method on days 1,3, 5, and 7 following ischemia-reperfusion injury.RESULTS： Compared with the control group, massive demyelination of the internal capsule occurred, and serum MBP content increased in the model group （P 〈 0.05）. Compared with the model group, the extent of demyelination in the internal capsule was less distinct and serum MBP content was significantly less in the early and late acupuncture group （P 〈 0.01 ）. Compared with the late acupuncture group, serum MBP content reached a peak later and the peak value was less in the early acupuncture group. CONCLUSION： Results suggest that acupuncture exerts a protective effect on injured cerebral myelin in ischemia-reperfusion rats by reducing serum MBP content and promoting remyelination. The study also suggests that the effect of early acupuncture is superior to late acupuncture.

Effect of minocycline on cerebral ischemia-reperfusion injury

Minocylcine, a tetracycline derivate, has been shown to cross the blood-brain barrier and enter the central nervous system. In this study, cerebral ischemia-reperfusion injury models were established using the suture method, and minocycline was immediately injected intraperitoneally after cerebral ischemia-repeffusion （22.5 mg/kg, initially 45 mg/kg） at a 12-hour interval. Results showed that after minocycline treatment, the volume of cerebral infarction was significantly reduced, the number of surviving cell in the hippocampal CA1 region increased, the number of apoptotic cells decreased, the expression of caspase-3 and poly（adenosine diphosphate-ribose） polymerase-1 protein was down-regulated, and the escape latency in the water maze test was significantly shortened compared with the ischemia-reperfusion group. Our experimental findings indicate that minocycline can protect against neuronal injury induced by focal ischemia-reperfusion, which may be mediated by the inhibition of caspase-3 and poly（adenosine diphosphate-ribose） polymerase-1 protein expression.

Expression of nerve growth factor precursor, mature nerve growth factor and their receptors during cerebral ischemia-reperfusion injury

We investigated nerve growth factor precursor （proNGF） and mature NGF expression in ischemic and non-ischemic cortices after cerebral ischemia-reperfusion injury. In both ischemic and non-ischemic cortices, proNGF was found to be present in the extracellular space and cytoplasm. In addition, mature NGF was expressed in extracellular space, but with a very low signal. In ischemic cortex only, proNGF was significantly decreased, reaching a minimal level at 1 day. Mature NGF was increased at 4 hours, then reached a minimal level at 3 days. The p75 neurotrophin receptor （p75NTR） was significantly decreased after ischemia, and increased at 3 days after ischemia. These results confirmed that proNGF was the predominant form of NGF during the pathological process of cerebral ischemia-repeffusion injury. In addition, our findings suggest that ischemic injury may influence the conversion of proNGF to mature NGF, and that proNGF/p75NTR may be involved in reperfusion injury.

Neuroprotective effect of penehyclidine hydrochloride on focal cerebral ischemia-reperfusion injury

Penehyclidine hydrochloride can promote microcirculation and reduce vascular permeability. However, the role of penehyclidine hydrochlodde in cerebral ischemia-reperfusion injury remains unclear. In this study, in vivo middle cerebral artery occlusion models were established in experimental rats, and penehyclidine hydrochloride pretreatment was given via intravenous injection prior to model establishment. Tetrazolium chloride, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling and immunohistochemical staining showed that, penehyclidine hydrochloride pretreatment markedly attenuated neuronal histopathological changes in the cortex, hippocampus and striatum, reduced infarction size, increased the expression level of BcI-2, decreased the expression level of caspase-3, and inhibited neuronal apoptosis in rats with cerebral ischemia-reperfusion injury. Xanthine oxidase and thiobarbituric acid chromogenic results showed that penehyclidine hydrochloride upregulated the activity of superoxide dismutase and downregulated the concentration of malondialdehyde in the ischemic cerebral cortex and hippocampus, as well as reduced the concentration of extracellular excitatory amino acids in rats with cerebral ischemia-reperfusion injury. In addition, penehyclidine hydrochloride inhibited the expression level of the NR1 subunit in hippocampal nerve cells in vitro following oxygen-glucose deprivation, as detected by PCR. Experimental findings indicate that penehyclidine hydrochloride attenuates neuronal apoptosis and oxidative stress injury after focal cerebral ischemia-reperfusion, thus exerting a neuroprotective effect.

Amyloid beta-peptide worsens cognitive impairment following cerebral ischemia-reperfusion injury

Amyloid 13-peptide, a major component of senile plaques in Alzheimer＇s disease, has been implicated in neuronal cell death and cognitive impairment. Recently, studies have shown that the pathogenesis of cerebral ischemia is closely linked with Alzheimer＇s disease. In this study, a rat model of global cerebral ischemia-reperfusion injury was established via occlusion of four arteries; meanwhile, fibrillar amyloid [3-peptide was injected into the rat lateral ventricle. The Morris water maze test and histological staining revealed that administration of amyloid 13-peptide could further aggravate impairments to learning and memory and neuronal cell death in the hippocampus of rats subjected to cerebral ischemia-reperfusion injury. Western blot showed that phosphorylation of tau protein and the activity of glycogen synthase kinase 313 were significantly stronger in cerebral ischemia-reperfusion injury rats subjected to amyloid [3-peptide administration than those undergo- ing cerebral ischemia-repetfusion or amyloid 13-peptide administration alone. Conversely, the activ- ity of protein phosphatase 2A was remarkably reduced in rats with cerebral ischemia-reperfusion injury following amyloid 13-peptide administration. These findings suggest that amyloid 13-peptide can potentiate tau phosphorylation induced by cerebral ischemia-reperfusion and thereby aggravate cognitive impairment.

Treatment with β-sitosterol ameliorates the effects of cerebral ischemia/reperfusion injury by suppressing cholesterol overload, endoplasmic reticulum stress, and apoptosis

β-Sitosterol is a type of phytosterol that occurs naturally in plants.Previous studies have shown that it has anti-oxidant,anti-hyperlipidemic,anti-inflammatory,immunomodulatory,and anti-tumor effects,but it is unknown whetherβ-sitosterol treatment reduces the effects of ischemic stroke.Here we found that,in a mouse model of ischemic stroke induced by middle cerebral artery occlusion,β-sitosterol reduced the volume of cerebral infarction and brain edema,reduced neuronal apoptosis in brain tissue,and alleviated neurological dysfunction;moreover,β-sitosterol increased the activity of oxygen-and glucose-deprived cerebral cortex neurons and reduced apoptosis.Further investigation showed that the neuroprotective effects ofβ-sitosterol may be related to inhibition of endoplasmic reticulum stress caused by intracellular cholesterol accumulation after ischemic stroke.In addition,β-sitosterol showed high affinity for NPC1L1,a key transporter of cholesterol,and antagonized its activity.In conclusion,β-sitosterol may help treat ischemic stroke by inhibiting neuronal intracellular cholesterol overload/endoplasmic reticulum stress/apoptosis signaling pathways.

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.

Protective Effect of GRK2 and Effect of Sanguis Draconis Flavones on Focal Cerebral Ischemia-Reperfusion Injury in Rats

[Objectives] To explore the protective effect of Sanguis Draconis flavones (SDF) on rat focal cerebral ischemia-reperfusion injury (CIRI) models established by middle cerebral artery occlusion (MCAO).[Methods] A total of 60 healthy adult male Sprague-Dawley rats were selected. They were evenly and randomly divided into sham group, model group, edaravone group (12 mg/kg) and SDF group (360 mg/kg), and administered intragastrically and intraperitoneally. The middle cerebral artery of each rat was blocked by suture-occluded method to establish a CIRI model. After ischemia for 2 h and reperfusion for 48 h, the pathological injury on the ischemic side was observed by HE staining;the neuron and myelin sheath structure was observed by transmission electron microscopy;the expression of G protein-coupled receptor kinase 2 (GRK2) was preserved by immunohistochemistry;and the transfer of GRK2 was detected by western-blot.[Results] After 48 h of CIRI, the nuclei of the penumbral cortical neurons shrank, the chromatin was unevenly distributed, the nuclear membrane was dissolved and the mitochondria in the cytoplasm were swollen and vacuolated. The myelin layer was disordered. With this change, the distribution of GRK2 subcellular cells in the penumbra of the injured lateral cortex transferred from the cytoplasm to the membrane. SDF can effectively restore neuronal and myelin sheath structural damage and reduce the functional (membrane coupling) expression of GRK2.[Conclusions] GRK2 may be an effective target for SDF to protect the impaired blood-brain barrier (BBB) in CIRI.

Effects of L-Tetrahydropalmatine on Neuron Apoptosis during Acute Cerebral Ischemia-Reperfusion of Rats

To investigate the effects of L-Tetrahydropalmatine (L-THP ) on neuron apoptosis during acute cerebral ischemia-reperfusion of rats and explore the effects of heat shock protein (HSP) on neuron apoptosis, Wistar rats were randomly divided into 3 groups: normal group, ischemia- reperfusion group and treatment group. The condition of neuron apoptosis, the survival state of neuron, pathological changes under an electron microscope and the number of HSP70 positive cells were measured in all groups. Results showed that the apoptosis neuron number was increased obviously at the 24th h during reperfusion and was further increased at the 48th h, the 72th h. While the number of survival neurons was decreased gradually with the prolongation of reperfusion time. Treatment with L-THP could decrease the apoptosis neuron number but increase the survival neuron number and the HSP70 positive cell number. Our study suggested that L-THP could decrease apoptosis and necrosis of neuron, up-regulate the expression of HSP70 and protect the cerebral ischemic injury.

Dopamine and cognitive function after global cerebral ischemia-reperfusion:a brief review

Global cerebral ischemia/hypoxia may occur due to various causes such as cardiac arrest,shock,and asphyxiation.Even though the patient’s life may be saved after cardiopulmonary resuscitation,cerebral ischemia– reperfusion injury is likely to occur and often results in neurological dysfunction.Apart from motor and speech impediments,patients with such injury may also suffer from impaired higher-level cognitive functions such as learning and memory,placing a heavy burden on families and society.Brain areas associated with the limbic system include the hippocampus,corpus striatum,and amygdala,which are linked with cognitive function.Those brain regions are easily damaged by hypoxia,and since they are connected with the dopaminergic pathway,global cerebral ischemia–reperfusion can damage the dopaminergic pathway as well and affect the projection of dopaminergic neurons in the limbic system.This review article examines the feasibility of using dopamine,a neurotransmitter heavily involved in cognitive function,in experimental research and clinical treatment of global cerebral ischemia–reperfusion injury.Specifically,we examine the effects of dopamine on post-injury cognition and neuronal plasticity,with the ultimate goal of identifying a new tool for clinical treatment.

Ligustrazine monomer against cerebral ischemia/reperfusion injury

Ligustrazine （2,3,5,6-tetramethylpyrazine） is a major active ingredient of the Szechwan lovage rhizome and is extensively used in treatment of ischemic cerebrovascular disease. The mecha- nism of action of ligustrazine use against ischemic cerebrovascular diseases remains unclear at present. This study summarizes its protective effect, the optimum time window of administra- tion, and the most effective mode of administration for clinical treatment of cerebral ischemia/ reperfusion injury. We examine the effects of ligustrazine on suppressing excitatory amino acid release, promoting migration, differentiation and proliferation of endogenous neural stem cells. We also looked at its effects on angiogenesis and how it inhibits thrombosis, the inflammatory response, and apoptosis after cerebral ischemia. We consider that ligustrazine gives noticeable protection from cerebral ischemia/reperfusion injury. The time window of ligustrazine admin- istration is limited. The protective effect and time window of a series of derivative monomers of ligustrazine such as 2-[（1,1-dimethylethyl）oxidoimino]methyl]-3,5,6-trimethylpyrazine, CXC137 and CXC 195 after cerebral ischemia were better than ligustrazine.

Autophagy: novel insights into therapeutic target of electroacupuncture against cerebral ischemia/reperfusion injury

Electroacupuncture is known as an effective adjuvant therapy in ischemic cerebrovascular disease. However, its underlying mechanisms remain unclear. Studies suggest that autophagy, which is essential for cell survival and cell death, is involved in cerebral ischemia reperfusion injury and might be modulate by electroacupuncture therapy in key ways. This paper aims to provide novel insights into a therapeutic target of electroacupuncture against cerebral ischemia/reperfusion injury from the perspective of autophagy. Here we review recent studies on electroacupuncture regulation of autophagy-related markers such as UNC-51-like kinase-1 complex, Beclin1, microtubule-associated protein-1 light chain 3, p62, and autophagosomes for treating cerebral ischemia/reperfusion injury. The results of these studies show that electroacupuncture may affect the initiation of autophagy, vesicle nucleation, expansion and maturation of autophagosomes, as well as fusion and degradation of autophagolysosomes. Moreover, studies indicate that electroacupuncture probably modulates autophagy by activating the mammalian target of the rapamycin signaling pathway.This review thus indicates that autophagy is a therapeutic target of electroacupuncture treatment against ischemic cerebrovascular diseases.

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.

Atorvastatin protects against cerebral ischemia/ reperfusion injury through anti-inflammatory and antioxidant effects

In addition to its lipid-lowering effect, atorvastatin exerts anti-inflammatory and antioxidant effects as well. In this study, we hypothesized that atorvastatin could protect against cerebral isch-emia/reperfusion injury. The middle cerebral artery ischemia/reperfusion model was established, and atorvastatin, 6.5 mg/kg, was administered by gavage. We found that, after cerebral ischemia/ reperfusion injury, levels of the inflammation-related factors E-selectin and myeloperoxidase were upregulated, the oxidative stress-related marker malondialdehyde was increased, and super- oxide dismutase activity was decreased in the ischemic cerebral cortex. Atorvastatin pretreatment significantly inhibited these changes. Our findings indicate that atorvastatin protects against ce-rebral ischemia/reperfusion injury through anti-inflammatory and antioxidant effects.