何首乌苷通过激活BDNF/TrkB信号通路拮抗H2O2诱导的大鼠海马神经元氧化损伤

探讨脑源性神经营养因子/酪氨酸激酶受体B(BDNF/TrkB)信号通路激活参与何首乌苷(PMG)对过氧化氢(H2O2)诱导神经元氧化应激损伤的保护作用。实验采用神经元原代培养,建立大鼠乳鼠海马神经元氧化应激损伤模型。实验结果显示高浓度的H2O2与MTT测定的细胞存活率降低相关,选择细胞存活率在40%~50%之间的200μmol/LH2O2浓度作为氧化应激损伤的实验浓度。与模型组相比,PMG预处理组(200μmol/L)可抑制H2O2诱导的神经元损伤(P<0.001)。TUNEL和β-微管蛋白III荧光染色显示PMG保护H2O2诱导的神经细胞损伤,明显降低细胞凋亡率(P<0.001),细胞骨架形态恢复正常。与PMG+H2O2预处理组相比较,当加入BDNF/TrkB信号转导通路阻断剂K252a后,PMG+H2O2+K252a组神经元细胞存活率大幅度下降(P<0.01),细胞骨架形态呈损伤状态。同时,我们发现PMG预处理恢复H2O2诱导的BDNF和P-TrkB的低表达水平,并且用K252a阻断BDNF/TrkB信号传导抑制了PMG对BDNF和P-TrkB表达水平的影响(P<0.01)。综上所述,何首乌苷可能通过激活BDNF/TrkB信号转导通路及维护神经元骨架的完整,实现对大鼠海马神经元氧化应激损伤的拮抗作用。     

LncRNA TUG1 inhibits neuronal apoptosis in status epilepticus rats via targeting the miR-421/mTOR axis

Status epilepticus (SE) induces apoptosis of hippocampal neurons. However, the underlying mechanism in SE is not fully understood. Recently, lncRNA TUG1 is reported as a significant mediator in neuronal development. In present study, we aimed to investigate whether lncRNA TUG1 induces apoptosis of hippocampal neurons in SE rat models. TUG1 expression in serum of normal volunteers and SE patients, SE rats and neurons with epileptiform discharge was detected. SE rat model was established and intervened with TUG1 to evaluate hippocampal neuronal apoptosis. The experiments in vitro were further performed in neurons with epileptiform discharge to verify the effects of TUG1 on neuronal apoptosis of SE rats. The downstream mechanism of TUG1 was predicted and verified. miR-421 was intervened to perform the rescue experiments. Levels of oxidative stress and inflammation-related factors and mTOR pathway-related proteins in SE rats and hippocampal neurons were detected. TUG1 was highly expressed in serum of SE patients, SE rats and neurons with epileptiform discharge. Inhibition of TUG1 relieved pathological injury, oxidative stress and inflammation and reduced neuronal apoptosis in SE rats, which were further verified in hippocampal neurons. TUG1 upregulated TIMP2 expression by targeting miR-421. Overexpressed miR-421 inhibited hippocampal neuronal apoptosis. TUG1 knockout inactivated the mTOR pathway via the miR-421/TIMP2 axis to relieve neuronal apoptosis, oxidative stress and inflammation in SE rats and hippocampal neurons. Taken together, these findings showed that downregulation of lncRNA TUG1 inhibited apoptosis of hippocampal neurons in SE rats, and attenuated oxidative stress and inflammation damage through regulating the miR-421/mTOR axis.     

miR-103a对癫痫大鼠海马组织星形胶质细胞活化的影响

为了考察miR-103a对癫痫大鼠海马组织星形胶质细胞活化的影响。本研究通过腹腔注射氯化锂和毛果芸香碱诱导癫痫大鼠模型,对大鼠脑室内注射miR-103a抑制剂来敲低miR-103a的表达;采用免疫组织化学染色检测大鼠海马组织中胶质纤维酸性蛋白(GFAP)的阳性表达;采用RT-qPCR和Western blotting方法检测大鼠海马组织中miR-103a、脑源性神经营养因子(BDNF)、GFAP、TNF-α和IL-6的m RNA和蛋白表达;苏木精-伊红(HE)染色评价海马组织病变程度;Nissl染色检测神经元存活情况;TUNEL染色检测神经元的凋亡。结果显示,癫痫大鼠海马组织中miR-103a被上调。下调miR-103a抑制癫痫大鼠海马组织中GFAP的mRNA和蛋白表达,且抑制癫痫大鼠海马神经元的病理损伤,但能促进癫痫大鼠海马神经元的存活并抑制其凋亡。此外,下调miR-103a还抑制癫痫大鼠海马组织中IL-6和TNF-α的表达,并促进癫痫大鼠海马组织中BDNF的表达。本研究表明,靶向沉默miR-103a可以抑制癫痫大鼠海马组织中星形胶质细胞的活化并改善神经元的病理损伤。     

Brain-derived neurotrophic factor can act as a pronecrotic factor through transcriptional and translational activation of NADPH oxidase

Several lines of evidence suggest that neurotrophins (NTs) potentiate or cause neuronal injury under various pathological conditions. Since NTs enhance survival and differentiation of cultured neurons in serum or defined media containing antioxidants, we set out experiments to delineate the patterns and underlying mechanisms of brain-derived neurotrophic factor (BDNF)-induced neuronal injury in mixed cortical cell cultures containing glia and neurons in serum-free media without antioxidants, where the three major routes of neuronal cell death, oxidative stress, excitotoxicity, and apoptosis, have been extensively studied. Rat cortical cell cultures, after prolonged exposure to NTs, underwent widespread neuronal necrosis. BDNF-induced neuronal necrosis was accompanied by reactive oxygen species (ROS) production and was dependent on the macromolecular synthesis. cDNA microarray analysis revealed that BDNF increased the expression of cytochrome b558, the plasma membrane-spanning subunit of NADPH oxidase. The expression and activation of NADPH oxidase were increased after exposure to BDNF. The selective inhibitors of NADPH oxidase prevented BDNF-induced ROS production and neuronal death without blocking antiapoptosis action of BDNF. The present study suggests that BDNF-induced expression and activation of NADPH oxidase cause oxidative neuronal necrosis and that the neurotrophic effects of NTs can be maximized under blockade of the pronecrotic action.     

Effect of HDAC Inhibitors on Neuroprotection and Neurite Outgrowth in Primary Rat Cortical Neurons Following Ischemic Insult

Histone deacetylase inhibitors (HDACi)—valproic acid (VPA) and trichostatin A (TSA) promote neurogenesis, neurite outgrowth, synaptic plasticity and neuroprotection. In this study, we investigated whether VPA and TSA promote post-ischemic neuroprotection and neuronal restoration in rat primary cortical neurons. On 6 days in vitro (DIV), cortical neurons were exposed to oxygen-glucose deprivation for 90 min. Cells were returned to normoxic conditions and cultured for 1, 3, or 7 days with or without VPA and TSA. Control cells were cultured in normoxic conditions only. On 7, 9, and 13 DIV, cells were measured neurite outgrowth using the Axiovision program and stained with Tunel staining kit. Microtubule associated protein-2 immunostaining and tunel staining showed significant recovery of neurite outgrowth and post-ischemic neuronal death by VPA or TSA treatment. We also determined levels of acetylated histone H3, PSD95, GAP 43 and synaptophysin. Significant increases in all three synaptic markers and acetylated histone H3 were observed relative to non-treated cells. Post-ischemic HDACi treatment also significantly raised levels of brain derived neurotrophic factor (BDNF) expression and secreted BDNF. Enhanced BDNF expression by HDACi treatment might have been involved in the post-ischemic neuroprotection and neuronal restorative effects. Our findings suggest that both VPA and TSA treatment during reoxygenation after ischemia may help post-ischemic neuroprotection and neuronal regeneration via increased BDNF expression and activation.     

Mdivi-1 Protects Epileptic Hippocampal Neurons from Apoptosis via Inhibiting Oxidative Stress and Endoplasmic Reticulum Stress in Vitro

Mitochondrial division inhibitor 1 (mdivi-1), a selective inhibitor of the mitochondrial fission protein dynamin-related protein 1, has been proposed to have a neuroprotective effect on hippocampal neurons in animal models of epilepsy. However, the effect of mdivi-1 on epileptic neuronal death in vitro remains unknown. Therefore, we investigated the effect of mdivi-1 and the underlying mechanisms in the hippocampal neuronal culture (HNC) model of acquired epilepsy (AE) in vitro. We found that mitochondrial fission was increased in the HNC model of AE and inhibition of mitochondrial fission by mdivi-1 significantly decreased neuronal apoptosis induced by AE. In addition, mdivi-1 pretreatment significantly attenuated oxidative stress induced by AE characterized by decrease of reactive oxygen species (ROS) production and malondialdehyde level and by increase of superoxide dismutase activity. Moreover, mdivi-1 pretreatment significantly decreased endoplasmic reticulum (ER) stress markers glucose-regulated protein 78, C/EBP homologous protein expression and caspase-3 activation. Altogether, our findings suggest that mdivi-1 protected against AE-induced hippocampal neuronal apoptosis in vitro via decreasing ROS-mediated oxidative stress and ER stress.     

Geranylgeranyltransferase I mediates BDNF‐induced synaptogenesis

Geranylgeranyltransferase I (GGT) is a prenyltransferase that mediates lipid modification of Rho small GTPases, such as Rho, Rac, and Cdc42, which are important for neuronal synaptogenesis. Although GGT is expressed in brain extensively, the function of GGT in central nerves system is largely unknown so far. We have previously demonstrated that GGT promotes the basal and neuronal activity and brain‐derived neurotrophic factor (BDNF)‐induced dendritic morphogenesis of cultured hippocampal neurons and cerebellar slices. This study is to explore the function and mechanism of GGT in neuronal synaptogenesis. We found that the protein level and activity of GGT gradually increased in rat hippocampus from P7 to P28 and subcellular located at synapse of neurons. The linear density of Synapsin 1 and post‐synaptic density protein 95 increased by over‐expression of GGT β, while reduced by inhibition or down‐regulation of GGT. In addition, GGT and its known substrate Rac was activated by BDNF, which promotes synaptogenesis in cultured hippocampal neurons. Furthermore, BDNF‐induced synaptogenesis was eliminated by GGT inhibition or down‐regulation, as well as by non‐prenylated Rac1 over‐expression. Together, our data suggested that GGT mediates BDNF‐induced neuronal synaptogenesis through Rac1 activation.     

远志皂苷对丙泊酚麻醉所致大鼠认知功能障碍的保护作用及机制

本研究旨在探讨远志皂苷对丙泊酚麻醉所致大鼠认知功能障碍的保护作用及机制。将SD大鼠分别应用远志皂苷(200 mL·kg^-1·d^-1)和/或丙泊酚(60 mL·kg^-1·d^-1)处理3周,通过Morris水迷宫实验来评价认知功能情况,通过苏木精伊红(hematoxylineosin, HE)染色评价组织病理改变。采用原位末端标记技术(TdTmediated dUTP nick and labeling, Tunel)检测大鼠海马神经细胞的凋亡情况。采用酶联免疫吸附法(enzymelinked immunosorbent assay, ELISA)检测氧化损伤指标。采用Western blotting检测Bcl-2和Caspase-3的表达。Morris水迷宫实验显示,远志皂苷显著降低了丙泊酚麻醉大鼠的逃避潜伏期,并提高了穿越平台次数(p<0.05)。苏木精伊红(HE)染色显示,远志皂苷可显著降低丙泊酚引起的大鼠海马组织病变程度。原位末端标记技术(Tunel)实验显示,远志皂苷抑制了丙泊酚引起的大鼠海马神经细胞凋亡(p<0.05)。Western blotting检测显示,远志皂苷抑制了丙泊酚对大鼠脑组织中Bcl-2蛋白的下调及Caspase-3的上调(p<0.05)。酶联免疫吸附检测显示,远志皂苷提高了大鼠脑组织中SOD和GSH的水平,并降低了MDA水平(p<0.05)。远志皂苷可显著改善丙泊酚麻醉大鼠的认知功能并降低海马组织病变程度,其机制与抑制海马神经细胞凋亡和减弱氧化损伤有关。     

Pterostilbene Attenuates Early Brain Injury Following Subarachnoid Hemorrhage via Inhibition of the NLRP3 Inflammasome and Nox2-Related Oxidative Stress

Pterostilbene (PTE), one of the polyphenols present in plants such as blueberries and grapes, has been suggested to have various effects, such as anti-oxidation, anti-apoptosis, and anti-cancer effects. Subarachnoid hemorrhage (SAH) is a severe neurological event known for its high morbidity and mortality. Recently, early brain injury (EBI) has been reported to play a significant role in the prognosis of patients with SAH. The present study aimed to investigate whether PTE could attenuate EBI after SAH was induced in C57BL/6 J mice. We also studied possible underlying mechanisms. After PTE treatment, the neurological score and brain water content of the mice were assessed. Oxidative stress and neuronal injury were also evaluated. Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activity was assessed using western blot analysis. Our results indicated that PTE treatment reduces the SAH grade, neurological score, and brain water content following SAH. PTE treatment also reduced NLRP3 inflammasome activation. PTE alleviated the oxidative stress following SAH as evidenced by the dihydroethidium staining, superoxide dismutase activity, malondialdehyde content, 3-nitrotyrosie and 8-hydroxy-2-deoxyguanosine levels, and gp91^phox and 4-hydroxynonenal expression levels. Additionally, PTE treatment reduced neuronal apoptosis. In conclusion, our study suggests that PTE attenuates EBI following SAH possibly via the inhibition of NLRP3 inflammasome and Nox2-related oxidative stress.     

Brain-derived neurotrophic factor mediates an excitoprotective effect of dietary restriction in mice

Dietary restriction (DR; reduced calorie intake) increases the lifespan of rodents and increases their resistance to cancer, diabetes and other age-related diseases. DR also exerts beneficial effects on the brain including enhanced learning and memory and increased resistance of neurons to excitotoxic, oxidative and metabolic insults. The mechanisms underlying the effects of DR on neuronal plasticity and survival are unknown. In the present study we show that levels of brain-derived neurotrophic factor (BDNF) are significantly increased in the hippocampus, cerebral cortex and striatum of mice maintained on an alternate day feeding DR regimen compared to animals fed ad libitum. Damage to hippocampal neurons induced by the excitotoxin kainic acid was significantly reduced in mice maintained on DR, and this neuroprotective effect was attenuated by intraventricular administration of a BDNF-blocking antibody. Our findings show that simply reducing food intake results in increased levels of BDNF in brain cells, and suggest that the resulting activation of BDNF signaling pathways plays a key role in the neuroprotective effect of DR. These results bolster accumulating evidence that DR may be an effective approach for increasing the resistance of the brain to damage and enhancing brain neuronal plasticity.     

Nuclear factor-kappaB mediates the cell survival-promoting action of activity-dependent neurotrophic factor peptide-9

Activity-dependent neurotrophic factor (ADNF) is produced by astrocytes in response to neuronal depolarization and, in turn, promotes neuronal survival. A nineamino acid ADNF peptide (ADNF9) exhibits full neurotrophic activity and potently protects cultured embryonic rat hippocampal neurons from oxidative injury and apoptosis. Picomolar concentrations of ADNF9 induced an increase in nuclear factor-kappaB (NF-kappaB) DNA-binding activity within 1 h of exposure, with a maximum increase of approximately 10-fold by 6 h. Activation of NF-kappaB was correlated with increased resistance of neurons to apoptosis induced by exposure to Fe(2+). The antiapoptotic action of ADNF9 was abolished when NF-kappaB activation was specifically blocked with kappaB decoy DNA. Oxidative stress was attenuated in neurons pretreated with ADNF9, and this effect of ADNF9 was blocked by kappaB decoy DNA, suggesting that ADNF9 suppresses apoptosis by reducing oxidative stress. ADNF9 also prevented neuronal apoptosis following trophic factor withdrawal via an NF-kappaB-mediated mechanism. Thus, NF-kappaB mediates the neuron survival-promoting effects of ADNF9 in experimental models relevant to developmental neuronal death and neurodegenerative disorders.     

Butylphthalide Suppresses Neuronal Cells Apoptosis and Inhibits JNK–Caspase3 Signaling Pathway After Brain Ischemia /Reperfusion in Rats

Although Butylphthalide (BP) has protective effects that reduce ischemia-induced brain damage and neuronal cell death, little is known about the precise mechanisms occurring during cerebral ischemia/reperfusion (I/R). Therefore, the aim of this study was to investigate the neuroprotective mechanisms of BP against ischemic brain injury induced by cerebral I/R through inhibition of the c-Jun N-terminal kinase (JNK)–Caspase3 signaling pathway. BP in distilled non-genetically modified Soybean oil was administered intragastrically three times a day at a dosage of 15 mg/(kg day) beginning at 20 min after I/R in Sprague–Dawley rats. Immunohistochemical staining and Western blotting were performed to examine the expression of related proteins, and TUNEL-staining was used to detect the percentage of neuronal apoptosis in the hippocampal CA1 region. The results showed that BP could significantly protect neurons against cerebral I/R-induced damage. Furthermore, the expression of p-JNK, p-Bcl2, p–c-Jun, FasL, and cleaved-caspase3 was also decreased in the rats treated with BP. In summary, our results imply that BP could remarkably improve the survival of CA1 pyramidal neurons in I/R-induced brain injury and inhibit the JNK–Caspase3 signaling pathway.     

Epigallocatechin-3-Gallate Ameliorated Iron Accumulation and Apoptosis and Promoted Neuronal Regeneration and Memory/Cognitive Functions in the Hippocampus Induced by Exposure to a Chronic High-Altitude Hypoxia Environment

We aimed to explore the protective effects and potential treatment mechanism of Epigallocatechin-3-gallate (EGCG) in an animal model of chronic exposure in a natural high-altitude hypoxia (HAH) environment. Behavioral alterations were assessed with the Morris water maze test. Iron accumulation in the hippocampus was detected by using DAB enhanced Perls’ staining, MRI, qPCR and colorimetry, respectively. Oxidative stress (malondialdehyde, MDA), apoptosis (Caspase-3), and neural regeneration (brain-derived neurotrophic factor, BDNF) were detected by using ELISA and western blotting. Neural ultrastructural changes were evaluated by transmission electron microscopy (TEM). The results showed that learning and memory performance of rats decreased when exposure to HAH environment. It was followed by iron accumulation, dysfunctional iron metabolism, reduced BDNF and the upregulation of MDA and Caspase-3. TEM confirmed the ultrastructural changes in neurons and mitochondria. EGCG reduced HAH-induced cognitive impairment, iron deposition, oxidative stress, and apoptosis and promoted neuronal regeneration against chronic HAH-mediated neural injury.

     

miR-139-5p upregulation alleviated spontaneous recurrent epileptiform discharge-induced oxidative stress and apoptosis in rat hippocampal neurons via regulating the Notch pathway

Epilepsy was characterized by the occurrence of spontaneous recurrent epileptiform discharges (SREDs) in neurons. Previous studies suggested that microRNA (miR)−139-5p and the Notch pathway were implicated in epilepsy; however, their interaction remained vague. Rat primary hippocampal neurons were isolated and identified by immunofluorescence staining. The cells were then used for SREDs model construction and further subjected to flow cytometry for apoptosis detection. Contents of lactate dehydrogenase (LDH), malondialdehyde (MDA), super oxidase dismutase (SOD) contents, and reactive oxygen species (ROS), and the level of mitochondrial membrane potential (MMP) were determined using commercial kits. Target gene and potential binding sites of miR-139-5p were predicted with TargetScan and confirmed by dual-luciferase reporter assay. Expressions of miR-139-5p, Notch pathway-related proteins and apoptosis-related proteins were measured by quantitative real-time polymerase chain reaction and western blot as needed. The results showed that the hippocampal neurons were microtubule-associated protein 2 (MAP2)-positive. miR-139-5p was downregulated in SREDs model cells. SREDs promoted apoptosis and increased the contents of LDH, MDA, and ROS and the level of MMP while reducing miR-139-5p expression and SOD content in cells, which was reversed by miR-139-5p overexpression. Notch-1 was recognized as the target gene of miR-139-5p, and its expression was negatively regulated by miR-139-5p. Besides, Notch-1 overexpression reversed the effects of miR-139-5p upregulation on the expressions of Notch pathway-related proteins and apoptosis-related proteins, cell apoptosis, oxidative stress and MMP in SREDs-treated cells. Our results indicated that miR-139-5p upregulation alleviated SREDs-induced oxidative stress and cell apoptosis via regulating the Notch pathway, which provides new insights into the role of miRNA in the occurrence and development of epilepsy.     

Regional distribution of brain-derived neurotrophic factor mRNA in the adult mouse brain.

Brain-derived neurotrophic factor (BDNF) is a protein that allows the survival of specific neuronal populations. This study reports on the distribution of the BDNF mRNA in the adult mouse brain, where the BDNF gene is strongly expressed, using quantitative Northern blot analysis and in situ hybridization. All brain regions examined were found to contain substantial amounts of BDNF mRNA, the highest levels being found in the hippocampus followed by the cerebral cortex. In the hippocampus, which is also the site of highest nerve growth factor (NGF) gene expression in the central nervous system (CNS), there is approximately 50-fold more BDNF mRNA than NGF mRNA. In other brain regions, such as the granule cell layer of the cerebellum, the differences between the levels of BDNF and NGF mRNAs are even more pronounced. The BDNF mRNA was localized by in situ hybridization in hippocampal neurons (pyramidal and granule cells). These data suggest that BDNF may play an important role in the CNS for a wide variety of adult neurons.     

Impact of treadmill running and sex on hippocampal neurogenesis in the mouse model of amyotrophic lateral sclerosis

Hippocampal neurogenesis in the subgranular zone (SGZ) of dentate gyrus (DG) occurs throughout life and is regulated by pathological and physiological processes. The role of oxidative stress in hippocampal neurogenesis and its response to exercise or neurodegenerative diseases remains controversial. The present study was designed to investigate the impact of oxidative stress, treadmill exercise and sex on hippocampal neurogenesis in a murine model of heightened oxidative stress (G93A mice). G93A and wild type (WT) mice were randomized to a treadmill running (EX) or a sedentary (SED) group for 1 or 4 wk. Immunohistochemistry was used to detect bromodeoxyuridine (BrdU) labeled proliferating cells, surviving cells, and their phenotype, as well as for determination of oxidative stress (3-NT; 8-OHdG). BDNF and IGF1 mRNA expression was assessed by in situ hybridization. Results showed that: (1) G93A-SED mice had greater hippocampal neurogenesis, BDNF mRNA, and 3-NT, as compared to WT-SED mice. (2) Treadmill running promoted hippocampal neurogenesis and BDNF mRNA content and lowered DNA oxidative damage (8-OHdG) in WT mice. (3) Male G93A mice showed significantly higher cell proliferation but a lower level of survival vs. female G93A mice. We conclude that G93A mice show higher hippocampal neurogenesis, in association with higher BDNF expression, yet running did not further enhance these phenomena in G93A mice, probably due to a 'ceiling effect' of an already heightened basal levels of hippocampal neurogenesis and BDNF expression.     

Pharmacological Inhibition of PERK Attenuates Early Brain Injury After Subarachnoid Hemorrhage in Rats Through the Activation of Akt

Neuronal apoptosis is a central pathological process in subarachnoid hemorrhage (SAH)-induced early brain injury. Endoplasmic reticulum (ER) stress was reported to have a vital role in the pathophysiology of neuronal apoptosis in the brain. The present study was designed to investigate the potential effects of ER stress and its downstream signals in early brain injury after SAH. One hundred thirty-four rats were subjected to an endovascular perforation model of SAH. The RNA-activated protein kinase-like ER kinase (PERK) inhibitor GSK2606414 and the Akt inhibitor MK2206 were injected intracerebroventricularly. SAH grade, neurologic scores, and brain water content were measured 72 h after subarachnoid hemorrhage. Expression of PERK and its downstream signals, Akt, Bcl-2, Bax, and cleaved caspase-3, were examined using Western blot analysis. Specific cell types that expressed PERK were detected with double immunofluorescence staining. Neuronal cell death was demonstrated with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL). Our results showed that the expression of p-PERK and its downstream targets, p-eIF2α and ATF4, increased after SAH and peaked at 72 h after SAH. PERK was expressed mostly in neurons. The inhibition of PERK with GSK2606414 reduced p-PERK, p-eIF2α, and ATF4 expression. Furthermore, GSK2606414 treatment increased p-Akt levels and the Bcl-2/Bax ratio as well as decreased cleaved caspase-3 expression and neuronal death, thereby improving neurological deficits at 72 h after SAH. The selective Akt inhibitor MK2206 abolished the beneficial effects of GSK2606414. PERK, the major transducer of ER stress, is involved in neuronal apoptosis after SAH. The inhibition of PERK reduces early brain injury via Akt-related anti-apoptosis pathways. PERK may serve as a promising target for future therapeutic intervention.     

Daphnetin protects hippocampal neurons from oxygen-glucose deprivation–induced injury

Daphnetin, a coumarin derivative extracted from Daphne odora var., was reported to possess a neuroprotective effect. Recently, it has been demonstrated that daphnetin attenuates ischemia/reperfusion (I/R) injury. However, the role of daphnetin in cerebral I/R injury and the potential mechanism have not been fully understood. The present study aimed to explore the regulatory roles of daphnetin on oxygen-glucose deprivation/reoxygenation (OGD/R)–induced cell injury in a model of hippocampal neurons. Our results demonstrated that daphnetin improved cell viability and reduced the lactate dehydrogenase leakage in OGD/R–stimulated hippocampal neurons. In addition, daphnetin inhibited oxidative stress and cell apoptosis in hippocampal neurons after OGD/R stimulation. Furthermore, daphnetin significantly enhanced the nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression in hippocampal neurons exposed to OGD/R. Knockdown of Nrf2 blocked the protective effect of daphnetin on OGD/R–induced hippocampal neurons. In conclusion, these findings demonstrated that daphnetin attenuated oxidative stress and neuronal apoptosis after OGD/R injury through the activation of the Nrf2/HO-1 signaling pathway in hippocampal neurons. Thus, daphnetin may be a novel therapeutic agent for cerebral I/R injury.