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.

Role of nitric oxide in cerebral ischemia/reperfusion injury:A biomolecular overview

Nitric oxide(NO)is a gaseous molecule produced by 3 different NO synthase(NOS)isoforms:Neural/brain NOS(nNOS/bNOS,type 1),endothelial NOS(eNOS,type 3)and inducible NOS(type 2).Type 1 and 3 NOS are constitutively expressed.NO can serve different purposes:As a vasoactive molecule,as a neurotransmitter or as an immunomodulator.It plays a key role in cerebral ischemia/reperfusion injury(CIRI).Hypoxic episodes simulate the production of oxygen free radicals,leading to mitochondrial and phospholipid damage.Upon reperfusion,increased levels of oxygen trigger oxide synthases;whose products are associated with neuronal damage by promoting lipid peroxidation,nitrosylation and excitotoxicity.Molecular pathways in CIRI can be altered by NOS.Neuroprotective effects are observed with eNOS activity.While nNOS interplay is prone to endothelial inflammation,oxidative stress and apoptosis.Therefore,nNOS appears to be detrimental.The interaction between NO and other free radicals develops peroxynitrite;which is a cytotoxic agent.It plays a main role in the likelihood of hemorrhagic events by tissue plasminogen activator(t-PA).Peroxynitrite scavengers are currently being studied as potential targets to prevent hemorrhagic transformation in CIRI.

Correlation between expression of two transforming growth factor-beta 1 receptors and microvascular density in a rat model of cerebral ischemia and reperfusion injury

The effects of transforming growth factor-β1 （TGF-β1） are currently controversial. Whether TGF-β1 promotes or inhibits revascularization under different conditions remains poorly understood. Based on previous studies, the current experiment established rat models of cerebral ischemia and reperfusion injury （IRI）, and demonstrated that pathological and functional damage was also increased after IRI. The most serious damage was observed at 3 days after reperfusion, at which time microvascular density fell to its lowest level. Soon afterwards, microvascular density increased, new collateral circulation was gradually established at 4 to 7 days after reperfusion, and pathological damage and neurological deficits were improved. TGF-β1, activin receptor-like kinase 5 （ALK5） mRNA and protein expression levels increased gradually over time. In contrast, ALK1 mRNA and protein expression decreased over the same period. A significant negative correlation was detected between microvascular density and expression of the ALK5 gene transcript. There was no correlation between microvascular density and ALK1 gene transcriptional expression following cerebral IRI in a rat model. These findings suggest that ALK5, rather than ALK1, is the critical receptor in the TGF-β1 signal pathways after cerebral IRI.

Effects of phycocyanin on apoptosis and expression of superoxide dismutase in cerebral ischemia reperfusion injury

BACKGROUND ： The application of exogenous antioxidant is always the focus in the prevention and treatment of cerebral ischemia. Phycocyanin has the effects against oxidation and inflammation, but its role in the pathophysiological process of cerebral ischemia reperfusion injury still needs further investigation. OBJECTIVE： To observe the effects of phycocyanin on the expression of superoxide dismutase （SOD） apoptosis and form of the nerve cells in rats after cerebral ischemia reperfusion injury. DESIGN： A randomized control animal experiment SETTING ： Institute of Cerebrovascular Disease, Medical School Hospital of Qingdao University MATERIALS： Fifty-two healthy adult male Wistar rats of clean degree, weighing 220-260 g, were used. Phycocyanin was provided by the Institute of Oceanology, Chinese Academy of Sciences. METHODS： The experiments were carried out in Shangdong Key Laboratory for Prevention and Treatment of Brain Diseases from May to December 2005. ① All the rats were divided into three groups according to the method of random number table： sham-operated group （n=4）, control group （n=24） and treatment group （n=24）. Models of middle cerebral artery occlusion/reperfusion （MCAO/R） were established by the introduction of thread through external and internal carotid arteries in the control group and treatment group. After 1-hour ischemia and 2-hour reperfusion, rats in the treatment group were administrated with gastric perfusion of phy- cocyanin suspension （0.1 mg/g）, and those in the control group were given saline of the same volume, and no treatment was given to the rats in the sham-operated group. ②The samples were removed and observed at ischemia for 1 hour and reperfusion for 6 and 12 hours and 1, 3, 7 and 14 days respectively in the control group and treatment group, 4 rats for each time point, and those were removed at 1 day postoperatively in the sham-operated group. Forms of the nerve cells were observed with toluidine blue staining. Apoptosis after cerebral ischemia reperfusion was detected with TUNEL technique. SOD expression was detected with immunohistochemical technique.③ The intergroup difference was compared with the ttest. MAIN OUTCOME MEASURES： The apoptosis of the nerve cells and SOD expression were mainly observed in each group. RESULTS： Finally, 52 rats were involved in the analysis of results. ① Number of apoptotic cells： In the sham-operated group, a few apoptotic cells could be observed in brain tissue. The apoptotic cells at each time point in the control group and treatment group were obviously more than those in the sham-operated group （P 〈 0.05）. In the treatment group, the numbers of apoptotic cells at 12 hours, 1 and 3 days after reperfusion were significantly fewer than those in the control group, and those at 6 hours, 7 and 14 days were similar to those in the control group. ② Number of SOD positive cells： In the sham-operated group, there was weak expression of SOD in brain tissue, and the positive cells were extremely few, the positive cells at each time point were significantly more in the control group and treatment group than in the sham-operated group （P 〈 0.05）. In the treatment group, the numbers of positive cells at 6 and 12 hours, 1 and 3 days after reperfusion were significantly fewer than those in the control group, and those at 7-14 days were similar to those in the control group. ③ Cellular forms： In the control group, the karyopyknosis occurred in the nerve cells, which were irregularly distributed, nucleolus disappeared, and some scattered cell fragments were observed. The forms of the nerve cells in the treatment group were generally normal. CONCLUSION ： Phycocyanin plays a neuroprotective role in cerebral ischemia reperfusion injury by activating the SOD expression and inhibiting apoptosis.

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.

Neuroprotective effects of rutaecarpine on cerebral ischemia reperfusion injury

Rutaecarpine, an active component of the traditional Chinese medicine Tetradium ruticarpum, has been shown to improve myocardial ischemia repeffusion injury. Because both cardiovascular and cerebrovascular diseases are forms of ischemic vascular disease, they are closely related. We hypothesized that rutaecarpine also has neuroprotective effects on cerebral ischemia reperfusion injury. A cerebral ischemia reperfusion model was established after 84, 252 and 504 pg/kg rutae- carpine were given to mice via intrapedtoneal injection, daily for 7 days. Results of the step through test, 2,3,5-triphenyl tetrazolium chloride dyeing and oxidative stress indicators showed that rutae- carpine could improve learning and memory ability, neurological symptoms and reduce infarction volume and cerebral water content in mice with cerebral ischemia reperfusion injury. Rutaecarpine could significantly decrease the malondialdehyde content and increase the activities of superoxide dismutase and glutathione peroxidase in mouse brain. Therefore, rutaecarpine could improve neu- rological function following injury induced by cerebral ischemia reperfusion, and the mechanism of this improvement may be associated with oxidative stress. These results verify that rutaecarpine has neuroprotective effects on cerebral ischemia reperfusion in mice.

Heat-sensitive moxibustion attenuates the inflammation after focal cerebral ischemia/ reperfusion injury

Heat-sensitive moxibustion has neuroprotective effects against focal cerebral ischemia/reperfusion injury, however its mechanism of action remains unclear. In this study, rat models of focal cerebral ischemia/reperfusion injury were treated with suspended moxibustion at acupoint Dazhui （DU14） for 35 minutes. Results showed that suspended moxibustion decreased infarct volume, reduced cortical myeloperoxidase activity, and suppressed serum levels of proinflammatory cytokines in rats with focal cerebral ischemia/reperfusion injury. Our experimental findings indicated that heat-sensitive moxibustion can attenuate inflammation and promote repair after focal cerebral ischemia/reperfusion injury.

Ultra-early treatment of bone marrow-derived mesenchymal stem cells for focal cerebral ischemia/ reperfusion injury

The time point at which bone marrow-derived mesenchymal stem cells（BMSCs）can be used in transplantation for the treatment of ischemic brain injury remains unclear.In the present study,BMSCs were transplanted to the ischemic site 90 minutes post-ischemia.The results demonstrated that the transplanted BMSCs improved neurological function,reduced infarct volume,increased survivin expression,decreased caspase-3 expression and reduced apoptosis.This suggests that BMSCs transplanted at an ultra-early stage ameliorated brain ischemia by increasing survivin expression,decreasing caspase-3 expression and reducing apoptosis at the ischemia/reperfusion injury site.

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.

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.

Cav3.2 channel regulates cerebral ischemia/reperfusion injury:a promising target for intervention

Calcium influx into neurons triggers neuronal death during cerebral ischemia/reperfusion injury.Various calcium channels are involved in cerebral ischemia/reperfusion injury.Cav3.2 channel is a main subtype of T-type calcium channels.T-type calcium channel blockers,such as pimozide and mibefradil,have been shown to prevent cerebral ischemia/reperfusion injury-induced brain injury.However,the role of Cav3.2 channels in cerebral ischemia/reperfusion injury remains unclear.Here,in vitro and in vivo models of cerebral ischemia/reperfusion injury were established using middle cerebral artery occlusion in mice and high glucose hypoxia/reoxygenation exposure in primary hippocampal neurons.The results showed that Cav3.2 expression was significantly upregulated in injured hippocampal tissue and primary hippocampal neurons.We further established a Cav3.2 gene-knockout mouse model of cerebral ischemia/reperfusion injury.Cav3.2 knockout markedly reduced infarct volume and brain water content,and alleviated neurological dysfunction after cerebral ischemia/reperfusion injury.Additionally,Cav3.2 knockout attenuated cerebral ischemia/reperfusion injury-induced oxidative stress,inflammatory response,and neuronal apoptosis.In the hippocampus of Cav3.2-knockout mice,calcineurin overexpression offset the beneficial effect of Cav3.2 knockout after cerebral ischemia/reperfusion injury.These findings suggest that the neuroprotective function of Cav3.2 knockout is mediated by calcineurin/nuclear factor of activated T cells 3 signaling.Findings from this study suggest that Cav3.2 could be a promising target for treatment of cerebral ischemia/reperfusion injury.

Effect of thyroid hormone on myocardial and cerebral ischemia reperfusion injury in valve replacement under cardiopulmonary bypass

Objective:To study the effect of thyroid hormone (euthyrox) on myocardial and cerebral ischemia reperfusion injury in valve replacement under cardiopulmonary bypass.Methods:A total of 76 patients who received valve replacement under cardiopulmonary bypass in our hospital between January 2013 and December 2016 were collected and divided into control group (n=38) and observation group (n=38) according to random number table. Observation group took euthyrox orally 1 week before surgery, control group took vitamin C tablets orally at the same point in time, and both therapies lasted for 1 week. Before taking medicine and after cardiopulmonary bypass (before end of surgery), serum levels of myocardial enzyme spectrum indexes and nerve injury indexes were compared between the two groups of patients. Results: Before taking medicine, differences in the serum levels of myocardial enzyme spectrum indexes and nerve injury indexes were not statistically significant between the two groups of patients. After cardiopulmonary bypass, serum myocardial enzyme spectrum indexes cTnT, CK-MB,α-HBD and LDH levels in observation group were lower than those in control group;serum nerve injury indexes NSE, S100B and GFAP levels were lower than those in control group while bFGF level was higher than that in control group.Conclusion: Euthyrox intervention in valve replacement under cardiopulmonary bypass can effectively reduce the myocardial and cerebral ischemia reperfusion injury.

Lactiplantibacillus plantarum AR113 alleviates microbiota dysbiosis of tongue coating and cerebral ischemia/reperfusion injury in rat

Stroke is one of the leading causes of death and disability worldwide.However,information on stroke-related tongue coating microbiome(TCM)is limited,and whether TCM modulation could benefit for stroke prevention and rehabilitation is unknown.Here,TCM from stroke patients(SP)was characterized using molecular techniques.The occurrence of stroke resulted in TCM dysbiosis with significantly reduced species richness and diversity.The abundance of Prevotella,Leptotrichia,Actinomyces,Alloprevotella,Haemophilus,and TM7_[G-1]were greatly reduced,but common infection Streptococcus and Pseudomonas were remarkably increased.Furthermore,an antioxidative probiotic Lactiplantibacillus plantarum AR113 was used for TCM intervention in stroke rats with cerebral ischemia/reperfusion(I/R).AR113 partly restored I/R induced change of TCM and gut microbiota with significantly improved neurological deficit,relieved histopathologic change,increased activities of antioxidant enzymes,and decreased contents of oxidative stress biomarkers.Moreover,the gene expression of antioxidant-related proteins and apoptosis-related factors heme oxygenase-1(HO-1),superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),nuclear factor erythroid 2-related factor 2(Nrf2),NAD(P)H:quinone oxidoreductase-1(NQO-1),and Bcl-2 was significantly increased,but cytochrome C,cleaved caspase-3,and Bax were markedly decreased in the brain by AR113 treatment.The results suggested that AR113 could ameliorate cerebral I/R injury through antioxidation and anti-apoptosis pathways,and AR113 intervention of TCM may have the application potential for stroke prevention and control.

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.

MicroRNA-670 aggravates cerebral ischemia/reperfusion injury via the Yap pathway

Apoptosis is an important programmed cell death process involved in ischemia/reperfusion injury.MicroRNAs are considered to play an important role in the molecular mechanism underlying the regulation of cerebral ischemia and reperfusion injury.However,whether miR-670 can regulate cell growth and death in cerebral ischemia/reperfusion and the underlying mechanism are poorly understood.In this study,we established mouse models of transient middle artery occlusion and Neuro 2a cell models of oxygen-glucose deprivation and reoxygenation to investigate the potential molecular mechanism by which miR-670 exhibits its effects during cerebral ischemia/reperfusion injury both in vitro and in vivo.Our results showed that after ischemia/reperfusion injury,miR-670 expression was obviously increased.After miR-670 expression was inhibited with an miR-670 antagomir,cerebral ischemia/reperfusion injury-induced neuronal death was obviously reduced.When miR-670 overexpression was induced by an miR-670 agomir,neuronal apoptosis was increased.In addition,we also found that miR-670 could promote Yap degradation via phosphorylation and worsen neuronal apoptosis and neurological deficits.Inhibition of miR-670 reduced neurological impairments after cerebral ischemia/reperfusion injury.These results suggest that microRNA-670 aggravates cerebral ischemia/reperfusion injury through the Yap pathway,which may be a potential target for treatment of cerebral ischemia/reperfusion injury.The present study was approved by the Institutional Animal Care and Use Committee of China Medical University on February 27,2017(IRB No.2017PS035K).

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.

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.

Electroacupuncture preconditioning protects against focal cerebral ischemia/reperfusion injury via suppression of dynamin-related protein 1

Electroacupuncture preconditioning at acupoint Baihui （GV20） can reduce focal cerebral ischemia/reperfusion injury. However, the precise protective mechanism remains unknown. Mitochondrial fission mediated by dynamin-related protein 1 （Drp1） can trigger neuronal apoptosis following cerebral ischemia/reperfusion injury. Herein, we examined the hypothesis that electroacupuncture pretreatment can regulate Drp1, and thus inhibit mitochondrial fission to provide cerebral protection. Rat models of focal cerebral ischemia/reperfusion injury were established by middle cerebral artery occlusion at 24 hours after 5 consecutive days of preconditioning with electroacupuncture at GV20 （depth 2 mm, intensity 1 mA, frequency 2/15 Hz, for 30 minutes, once a day）. Neurological function was assessed using the Longa neurological deficit score. Pathological changes in the ischemic penumbra on the injury side were assessed by hematoxylin-eosin staining. Cellular apoptosis in the ischemic penumbra on the injury side was assessed by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling staining. Mitochondrial ultrastructure in the ischemic penumbra on the injury side was assessed by transmission electron microscopy. Drp1 and cytochrome c expression in the ischemic penumbra on the injury side were assessed by western blot assay. Results showed that electroacupuncture preconditioning decreased expression of total and mitochondrial Drp1, decreased expression of total and cytosolic cytochrome c, maintained mitochondrial morphology and reduced the proportion of apoptotic cells in the ischemic penumbra on the injury side, with associated improvements in neurological function. These data suggest that electroacupuncture preconditioning-induced neuronal protection involves inhibition of the expression and translocation of Drp1.

Electroacupuncture reduces apoptotic index and inhibits p38 mitogen-activated protein kinase signaling pathway in the hippocampus of rats with cerebral ischemia/reperfusion injury

Electroacupuncture attenuates cerebral hypoxia and neuronal apoptosis induced by cerebral ischemia/reperfusion injury.To further identify the involved mechanisms,we assumed that electroacupuncture used to treat cerebral ischemia/reperfusion injury was associated with the p38 mitogen-activated protein kinase（MAPK） signaling pathway.We established rat models of cerebral ischemia/reperfusion injury using the modified Zea-Longa＇s method.At 30 minutes before model establishment,p38 MAPK blocker SB20358 was injected into the left lateral ventricles.At 1.5 hours after model establishment,electroacupuncture was administered at acupoints of Chize（LU5）,Hegu（LI4）,Zusanli（ST36）,and Sanyinjiao（SP6） for 20 minutes in the affected side.Results showed that the combination of EA and SB20358 injection significantly decreased neurologic impairment scores,but no significant differences were determined among different interventional groups.Hematoxylin-eosin staining also showed reduced brain tissue injuries.Compared with the SB20358 group,the cells were regularly arranged,the structures were complete,and the number of viable neurons was higher in the SB20358 ＋ electroacupuncture group.Terminal deoxynucleotidyl transferase（Td T）-mediated d UTP nick-end labeling assay showed a decreased apoptotic index in each group,with a significant decrease in the SB20358 ＋ electroacupuncture group.Immunohistochemistry revealed reduced phosphorylated p38 expression at 3 days in the electroacupuncture group and SB20358 ＋ electroacupuncture group compared with the ischemia/reperfusion group.There was no significant difference in phosphorylated p38 expression between the ischemia/reperfusion group and SB20358 group.These findings confirmed that the electroacupuncture effects on mitigating cerebral ischemia/reperfusion injury are possibly associated with the p38 MAPK signaling pathway.A time period of 3 days could promote the repair of ischemic cerebral nerves.