Oxygen-glucose Deprivation Followed By Reoxygenation Research Articles

Piceatannol upregulates USP14-mediated GPX4 deubiquitination to inhibit neuronal ferroptosis caused by cerebral ischemia-reperfusion in mice.

Ischemic stroke is a very common brain disorder. This study aims to assess the neuroprotective effects of piceatannol (PCT) in preventing neuronal injury resulting from cerebral ischemia and reperfusion (I/R) in mice. Additionally, we investigated the underlying mechanisms through which PCT inhibits neuronal ferroptosis by modulating the USP14/GPX4 signaling axis. In vitro and in vivo experiments were conducted. In vitro, oxygen-glucose deprivation followed by reoxygenation (OGD/R) was used to simulate ischemic injury in neuronal cells. We utilized various techniques, including DCFH-DA staining, FeRhoNox-1 staining, MDA and GSH determination, immunofluorescence, Western blotting, co-immunoprecipitation, plasmid and siRNA transfection, to evaluate the therapeutic efficacy of PCT and elucidate its mechanism of action. For vivo studies, we established a mouse model of I/R by ligating the bilateral common carotid arteries. The efficacy of PCT in mitigating brain injury and cognitive dysfunction were assessed through behavioral tests, histological analysis, Western blotting, and immunohistochemistry. PCT treatment significantly enhanced cell viability under OGD/R and reduced lipid peroxidation by decreasing levels of ROS, MDA. Furthermore, PCT effectively inhibited neuronal ferroptosis by modulating the expression of key ferroptosis-related proteins, including GPX4, ACSL4, FPN1, and Ferritin. Mechanistically, PCT was found to prevent GPX4 degradation through USP14-mediated deubiquitination. Notably, silencing USP14 reversed the ferroptotic effects of PCT, whereas overexpressing of USP14 amplified these effects. In vivo, PCT significantly reduced pathological damage of brain tissue and improved cognitive dysfunction. Piceatannol exerts neuroprotective effects by regulating ferroptosis through the USP14/GPX4 axis, thereby preventing cerebral ischemia/reperfusion injury.

Human neural stem cells derived from fetal human brain communicate with each other and rescue ischemic neuronal cells through tunneling nanotubes

Pre-clinical trials have demonstrated the neuroprotective effects of transplanted human neural stem cells (hNSCs) during the post-ischemic phase. However, the exact neuroprotective mechanism remains unclear. Tunneling nanotubes (TNTs) are long plasma membrane bridges that physically connect distant cells, enabling the intercellular transfer of mitochondria and contributing to post-ischemic repair processes. Whether hNSCs communicate through TNTs and their role in post-ischemic neuroprotection remains unknown. In this study, non-immortalized hNSC lines derived from fetal human brain tissues were examined to explore these possibilities and assess the post-ischemic neuroprotection potential of these hNSCs. Using Tau-STED super-resolution confocal microscopy, live cell time-lapse fluorescence microscopy, electron microscopy, and direct or non-contact homotypic co-cultures, we demonstrated that hNSCs generate nestin-positive TNTs in both 3D neurospheres and 2D cultures, through which they transfer functional mitochondria. Co-culturing hNSCs with differentiated SH-SY5Y (dSH-SY5Y) revealed heterotypic TNTs allowing mitochondrial transfer from hNSCs to dSH-SY5Y. To investigate the role of heterotypic TNTs in post-ischemic neuroprotection, dSH-SY5Y were subjected to oxygen-glucose deprivation (OGD) followed by reoxygenation (OGD/R) with or without hNSCs in direct or non-contact co-cultures. Compared to normoxia, OGD/R dSH-SY5Y became apoptotic with impaired electrical activity. When OGD/R dSH-SY5Y were co-cultured in direct contact with hNSCs, heterotypic TNTs enabled the transfer of functional mitochondria from hNSCs to OGD/R dSH-SY5Y, rescuing them from apoptosis and restoring the bioelectrical profile toward normoxic dSH-SY5Y. This complete neuroprotection did not occur in the non-contact co-culture. In summary, our data reveal the presence of a functional TNTs network containing nestin within hNSCs, demonstrate the involvement of TNTs in post-ischemic neuroprotection mediated by hNSCs, and highlight the strong efficacy of our hNSC lines in post-ischemic neuroprotection.Human neural stem cells (hNSCs) communicate with each other and rescue ischemic neurons through nestin-positive tunneling nanotubes (TNTs). A Functional mitochondria are exchanged via TNTs between hNSCs. B hNSCs transfer functional mitochondria to ischemic neurons through TNTs, rescuing neurons from ischemia/reperfusion ROS-dependent apoptosis.

Melatonin Attenuates Ischemic-like Cell Injury by Promoting Autophagosome Maturation via the Sirt1/FoxO1/Rab7 Axis in Hippocampal HT22 Cells and in Organotypic Cultures.

Dysfunctional autophagy is linked to neuronal damage in ischemia/reperfusion injury. The Ras-related protein 7 (Rab7), a member of the Rab family of small GTPases, appears crucial for the progression of the autophagic flux, and its activity is strictly interconnected with the histone deacetylase Silent information regulator 1 (Sirt1) and transcription factor Forkhead box class O1 (FoxO1). The present study assessed the neuroprotective role of melatonin in the modulation of the Sirt1/FoxO1/Rab7 axis in HT22 cells and organotypic hippocampal cultures exposed to oxygen-glucose deprivation followed by reoxygenation (OGD/R). The results showed that melatonin re-established physiological levels of autophagy and reduced propidium iodide-positive cells, speeding up autophagosome (AP) maturation and increasing lysosomal activity. Our study revealed that melatonin modulates autophagic pathways, increasing the expression of both Rab7 and FoxO1 and restoring the Sirt1 expression affected by OGD/R. In addition, the Sirt1 inhibitor EX-527 significantly reduced Rab7, Sirt1, and FoxO1 expression, as well as autolysosomes formation, and blocked the neuroprotective effect of melatonin. Overall, our findings provide, for the first time, new insights into the neuroprotective role of melatonin against ischemic injury through the activation of the Sirt1/FoxO1/Rab7 axis.

Effects and mechanisms of 6-hydroxykaempferol 3,6-di-O-glucoside-7-O-glucuronide from Safflower on endothelial injury in vitro and on thrombosis in vivo.

Background: The florets of Carthamus tinctorius L. (Safflower) is an important traditional medicine for promoting blood circulation and removing blood stasis. However, its bioactive compounds and mechanism of action need further clarification. Objective: This study aims to investigate the effect and possible mechanism of 6-hydroxykaempferol 3,6-di-O-glucoside-7-O-glucuronide (HGG) from Safflower on endothelial injury in vitro, and to verify its anti-thrombotic activity in vivo. Methods: The endothelial injury on human umbilical vein endothelial cells (HUVECs) was induced by oxygen-glucose deprivation followed by reoxygenation (OGD/R). The effect of HGG on the proliferation of HUVECs under OGD/R was evaluated by MTT, LDH release, Hoechst-33342 staining, and Annexin V-FITC apoptosis assay. RNA-seq, RT-qPCR, Enzyme-linked immunosorbent assay and Western blot experiments were performed to uncover the molecular mechanism. The anti-thrombotic effect of HGG in vivo was evaluated using phenylhydrazine (PHZ)-induced zebrafish thrombosis model. Results: HGG significantly protected OGD/R induced endothelial injury, and decreased HUVECs apoptosis by regulating expressions of hypoxia inducible factor-1 alpha (HIF-1α) and nuclear factor kappa B (NF-κB) at both transcriptome and protein levels. Moreover, HGG reversed the mRNA expression of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α, and reduced the release of IL-6 after OGD/R. In addition, HGG exhibited protective effects against PHZ-induced zebrafish thrombosis and improved blood circulation. Conclusion: HGG regulates the expression of HIF-1α and NF-κB, protects OGD/R induced endothelial dysfunction in vitro and has anti-thrombotic activity in PHZ-induced thrombosis in vivo.

Overexpression of Mitochondrial Ferritin Enhances Blood-Brain Barrier Integrity Following Ischemic Stroke in Mice by Maintaining Iron Homeostasis in Endothelial Cells.

Blood–brain barrier (BBB) breakdown, a characteristic feature of ischemic stroke, contributes to poor patient outcomes. Brain microvascular endothelial cells (BMVECs) are a key component of the BBB and dysfunction or death of these cells following cerebral ischemia reperfusion (I/R) injury can disrupt the BBB, leading to leukocyte infiltration, brain edema and intracerebral hemorrhage. We previously demonstrated that mitochondrial ferritin (FtMt) can alleviate I/R-induced neuronal ferroptosis by inhibiting inflammation-regulated iron deposition. However, whether FtMt is involved in BBB disruption during cerebral I/R is still unknown. In the present study, we found that FtMt expression in BMVECs is upregulated after I/R and overexpression of FtMt attenuates I/R-induced BBB disruption. Mechanistically, we found that FtMt prevents tight junction loss and apoptosis by inhibiting iron dysregulation and reactive oxygen species (ROS) accumulation in I/R-treated BMVECs. Chelating excess iron with deferoxamine alleviates apoptosis in the brain endothelial cell line bEnd.3 under oxygen glucose deprivation followed by reoxygenation (OGD/R) insult. In summary, our data identify a previously unexplored effect for FtMt in the BBB and provide evidence that iron-mediated oxidative stress in BMVECs is an early cause of BMVECs damage and BBB breakdown in ischemic stroke.

Melatonin reshapes the mitochondrial network and promotes intercellular mitochondrial transfer via tunneling nanotubes after ischemic-like injury in hippocampal HT22 cells.

Mitochondrial dysfunction is considered one of the hallmarks of ischemia/reperfusion injury. Mitochondria are plastic organelles that undergo continuous biogenesis, fusion, and fission. They can be transferred between cells through tunneling nanotubes (TNTs), dynamic structures that allow the exchange of proteins, soluble molecules, and organelles. Maintaining mitochondrial dynamics is crucial to cell function and survival. The present study aimed to assess the effects of melatonin on mitochondrial dynamics, TNT formation, and mitochondria transfer in HT22 cells exposed to oxygen/glucose deprivation followed by reoxygenation (OGD/R). The results showed that melatonin treatment during the reoxygenation phase reduced mitochondrial reactive oxygen species (ROS) production, improved cell viability, and increased the expression of PGC1α and SIRT3. Melatonin also preserved the expression of the membrane translocase proteins TOM20 and TIM23, and of the matrix protein HSP60, which are involved in mitochondrial biogenesis. Moreover, it promoted mitochondrial fusion and enhanced the expression of MFN2 and OPA1. Remarkably, melatonin also fostered mitochondrial transfer between injured HT22 cells through TNT connections. These results provide new insights into the effect of melatonin on mitochondrial network reshaping and cell survival. Fostering TNTs formation represents a novel mechanism mediating the protective effect of melatonin in ischemia/reperfusion injury.

Prenatal electronic cigarette exposure decreases brain glucose utilization and worsens outcome in offspring hypoxic-ischemic brain injury.

It has been shown that prenatal nicotine and tobacco smoke exposure can cause different neurobehavioral disorders in the offspring. We hypothesize that prenatal exposure to nicotine-containing electronic cigarette (e-Cig) vapor can predispose newborn to enhanced sensitivity to hypoxic-ischemic (HI) brain injury and impaired motor and cognitive functions. In this study, pregnant CD1 mice were exposed to e-Cig vapor (2.4% nicotine). Primary cortical neurons isolated from e-Cig exposed fetus were exposed to oxygen-glucose deprivation followed by reoxygenation (OGD/R) to mimic HI brain injury. Cell viability and glucose utilization were analyzed in these neurons. HI brain injury was induced in 8-9-day-old pups. Short-term brain injury was evaluated by triphenyltetrazolium chloride staining. Long-term motor and cognitive functions were evaluated by open field, novel object recognition, Morris water maze, and foot fault tests. Western blotting and immunofluorescence were done to characterize glucose transporters in offspring brain. We found that e-Cig exposed neurons demonstrated decreased cell viability and glucose utilization in OGD/R. Prenatally e-Cig exposed pups also had increased brain injury and edema 24hr after HI brain injury. Further, in utero e-Cig exposed offspring with HI brain injury displayed impaired memory, learning, and motor coordination at adolescence. Additionally, the expression of glucose transporters decreased in e-Cig exposed offspring brain after HI brain injury. These results indicate that reduced glucose utilization can contribute to prenatal e-Cig exposure induced worsened HI brain injury in offspring. This study is instrumental in elucidating the possible deleterious effects of e-Cig use in the general population.

Neuroprotective Effect of Metaplexis japonica against in vitro Ischemia Model

Metaplexis japonica (Apocynaceae) is a perennial herb, extensively used in traditional medicinal system for various diseases. The purpose of the study was to evaluate the protective effect of M. japonica against in vitro ischemia. In the present study, 70% ethanol extract of M. japonica was fractionated with different polarity solvents. For in vitro ischemia, oxygen-glucose deprivation followed by reoxygenation (OGD-R) in cells was used to investigate the effects of M. japonica and its fractions. For oxidative stress model, Hydrogen peroxide (H2 O2 ) induced cell death was studied in HT22 cell line. M. japonica and its fractions significantly reduced the HT22 cell damage, which was induced by 4 hrs of OGD followed by 24 hrs of reoxygenation and 24 hrs of H2 O2, respectively. The effectiveness of ethyl acetate fraction was higher than other fractions/crude extract. Our results suggest that M. japonica could be a neuroprotective agent for the treatment of stroke.
 Key words: Metaplexis japonica, Stroke, Oxygen-glucose deprivation, Neuroprotection

RTN1-C is involved in high glucose-aggravated neuronal cell subjected to oxygen-glucose deprivation and reoxygenation injury via endoplasmic reticulum stress

BackgroundPatients suffering from diabetes mellitus experience poor outcomes after ischemic stroke. RTN1-C, ER-associated proteins localized in endoplasmic reticulum (ER) membrane, plays an important role in ER stress-induced apoptosis and regulates cellular susceptibility to different apoptosis pathways. Overexpression of RTN1-C can aggravate cerebral ischemia/reperfusion injury (IRI). ER stress plays a crucial role in hyperglycemia-aggravated cerebral IRI. In this study, we aimed to investigate the role of RTN1-C in high glucose-aggravated OGD/R-induced cell damage. Materials and methodsN2a cells and primary neuronal cells were cultured in normal glucose or high glucose conditions. We used a model of oxygen-glucose deprivation followed by reoxygenation (OGD/R). RTN1-C shRNA was used to knock down RTN1-C. The chemical chaperone 4-phenylbutyric acid (4-PBA) is a low molecular weight fatty acid that has the ability to stabilize mutant proteins and facilitate their folding, was used to inhibited ER stress. Cell viability and apoptosis were measured by CCK-8 and flow cytometry assays. The contents of ER stress-associated proteins, such as GRP78, cleaved caspase-12, CHOP and cleaved caspase-3, were detected by western blot. ResultsHigh glucose significantly decreased cell viability and increased cell apoptosis in OGD/R-treated neuronal cells. The contents of GRP78, cleaved caspase-12, CHOP and cleaved caspase-3 under high glucose conditions were higher than those under normal glucose conditions after OGD/R. Importantly, inhibition of ER stress by 4-PBA alleviated the high glucose-aggravated OGD/R-induced cell damage. Here, we demonstrated that high glucose increases RTN1-C expression in OGD/R-treated cells. More importantly, knockdown of RTN1-C expression dramatically reversed the high glucose-aggravated change in cell viability and apoptosis and relieved ER stress in OGD/R-treated cells. ConclusionsHigh glucose significantly increases RTN1-C expression in OGD/R-treated cells. RTN1-C affects high glucose-treated OGD/R cells by exacerbating ER stress.

Maternal Electronic Cigarette Use Can Enhance Offspring Susceptibility to Hypoxic‐Ischemic Brain Injury

Prenatal exposure to tobacco smoke and nicotine is believed to interfere with fetal brain development predisposing offspring to different neurobehavioral and neuropsychological disorders. Included in this is increased neonatal vulnerability to hypoxic‐ischemic encephalopathy (HIE) which is a major cause of neonatal death and child disability in the US. These effects could be, in part, mediated by fetal nicotine exposure. Use of electronic cigarettes (e‐Cigs), commonly known as vaping, has been rapidly increasing in recent times in the general population, including women of reproductive age. E‐Cig use during pregnancy is also increasing because of the addictive properties of nicotine along with the perception of the relative safety of e‐Cigs. In this study, we aimed to investigate the effects of maternal e‐Cig use on neonatal brain development and HIE utilizing a combination of in vitro and in vivo models. Pregnant CD1 mice were exposed to e‐Cig vapor (2.4% nicotine). Primary cortical neurons were isolated from e‐Cig exposed fetus and cultured for seven days with subsequent exposure to oxygen‐glucose deprivation followed by reoxygenation (OGD/R) to mimic ischemia‐reperfusion injury. Hypoxic‐ischemic brain injury was induced in 8–9 days old mouse pups by a combination of left common carotid artery ligation and 15 minutes exposure to 8% oxygen. We found that e‐Cig exposed cortical neurons demonstrated decreased cell viability and increased caspase‐3 expression in OGD/R condition. These effects were accompanied by a decrease in neurite formation, mitochondrial dysfunctions, and decreased glucose uptake & glucose transporter expression in OGD/R condition. Our preliminary data also indicate increased sensitivity to HI brain injury in prenatally e‐Cig exposed mouse pups. Additionally, in utero e‐Cig exposed mice offspring displayed a significantly increased level of hyperactivity at postnatal day 45 in open field test. These results indicate that maternal e‐Cig exposure could lead to offspring behavioral abnormalities and enhance HI brain injury. Further studies are needed to demonstrate the long‐term anatomical and behavioral effects of HI brain injury in e‐Cig exposed offspring pups. This study is instrumental in elucidating the possible deleterious effects of maternal e‐Cig use in the general population.Support or Funding InformationR01 DA029121This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Minocycline protects against myocardial ischemia/reperfusion injury in rats by upregulating MCPIP1 to inhibit NF-κB activation.

Minocycline is a tetracycline antibiotic and has been shown to play a protective role in cerebral and myocardial ischemia/reperfusion (I/R). However, the underlying mechanism remains unclear. Herein, we investigated whether monocyte chemotactic protein-induced protein-1 (MCPIP1), a negative regulator of inflammation, was involved in the minocycline-induced cardioprotection in myocardial I/R in vivo and in vitro models. Myocardial ischemia was induced in rats by left anterior descending coronary artery occlusion for 1 h and followed by 48 h reperfusion. Minocycline was administered prior to ischemia (45 mg/kg, ip, BID, for 1 d) and over the course of reperfusion (22.5 mg/kg, ip, BID, for 2 d). Cardiac function and infarct sizes were assessed. Administration of minocycline significantly decreased the infarct size, alleviated myocardial cell damage, elevated left ventricle ejection fraction, and left ventricle fractional shortening following I/R injury along with significantly decreased pro-inflammatory cytokine IL-1β and monocyte chemoattractant protein-1 (MCP-1) levels in heart tissue. H9c2 cardiomyocytes were subjected to oxygen glucose deprivation (OGD) followed by reoxygenation (OGD/R). Pretreatment with minocycline (1-50 μmol/L) dose-dependently increased the cell viability and inhibited OGD/R-induced expression of MCP-1 and IL-6. Furthermore, minocycline dose-dependently inhibited nuclear translocation of NF-κB p65 in H9c2 cells subjected to OGD/R. In both the in vivo and in vitro models, minocycline significantly increased MCPIP1 protein expression; knockdown of MCPIP1 with siRNA in H9c2 cells abolished all the protective effects of minocycline against OGD/R-induced injury. Our results demonstrate that minocycline alleviates myocardial I/R injury via upregulating MCPIP1, then subsequently inhibiting NF-κB activation and pro-inflammatory cytokine secretion.

RTN1-C mediates cerebral ischemia/reperfusion injury via ER stress and mitochondria-associated apoptosis pathways

The reticulon family has been found to induce apoptosis, inhibit axon regeneration and regulate protein trafficking. However, little is known about the mechanisms of how reticulon proteins are involved in neuronal death-promoting processes during ischemia. Here, we report that the expression of Reticulon Protein 1-C (RTN1-C) was associated with the progression of cerebral ischemia/reperfusion (I/R) injury. Using a combination of rat middle cerebral artery occlusion (MCAO) stroke and oxygen-glucose deprivation followed by reoxygenation (OGD/R) models, we determined that the expression of RTN1-C was significantly increased during cerebral ischemic/reperfusion. RTN1-C overexpression induced apoptosis and increased the cell vulnerability to ischemic injury, whereas RTN1-C knockdown reversed ischemia-induced apoptosis and attenuated the vulnerability of OGD/R-treated neural cells. Mechanistically, we demonstrated that RTN1-C mediated OGD/R-induced apoptosis through ER stress and mitochondria-associated pathways. RTN1-C interacted with Bcl-xL and increased its localization in the ER, thus reducing the anti-apoptotic activity of Bcl-xL. Most importantly, knockdown of Rtn1-c expression in vivo attenuated apoptosis in MCAO rats and reduced the extent of I/R-induced brain injury, as assessed by infarct volume and neurological score. Collectively, these data support for the first time that RTN1-C may represent a novel candidate for therapies against cerebral ischemia/reperfusion injury.

Isoquercetin activates the ERK1/2-Nrf2 pathway and protects against cerebral ischemia-reperfusion injury in vivo and in vitro.

Isoquercetin has exhibited a wide range of therapeutic properties, including antioxidant, anti-inflammatory and anti-allergic activities. The aim of the present study was to investigate the effect of isoquercetin on rats with 2 h middle cerebral artery occlusion (MCAO) and evaluate the neuroprotective effect of isoquercetin on a primary culture of rat hippocampal neuronal cells subjected to oxygen-glucose deprivation followed by reoxygenation (OGD/R). In vivo, the rats treated with isoquercetin exhibited a lower degree of neurological dysfunction and smaller infarct volume than the vehicle-treated rats. In vitro, it was found that isoquercetin prevented the OGD/R-induced increase in apoptosis, lactate dehydrogenase release and reduction in cell viability. Additionally, isoquercetin induced the upregulation of nuclear factor erythroid 2-related factor 2 gene and protein expression, and increased extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation. This indicates that the ERK1/2 pathway may contribute to the neuroprotective effect of isoquercetin against OGD/R-induced oxidative damage in rat hippocampal neurons. These findings suggest the potential importance of isoquercetin in the treatment of ischemia/reperfusion-related brain injury and associated diseases.

Neuroserpin Protects Rat Neurons and Microglia-Mediated Inflammatory Response Against Oxygen-Glucose Deprivation- and Reoxygenation Treatments in an In Vitro Study

Background/Aims: Neuroserpin (NSP) is known for its neuroprotective role in cerebral ischemic animal models and patients. Our laboratory conducted a series of investigations on the neuroprotection of NSP in different cells in the brain. In the present study, we further observe the effects of NSP on neurons and microglia-mediated inflammatory response following oxygen-glucose deprivation (OGD), and explore possible mechanisms related to neuroprotection of OGD in the central nervous system (CNS). Methods: Neurons and microglia from neonatal rats were treated with OGD followed by reoxygenation (OGD/R). To confirm the effects of NSP, the neuronal survival, neuronal apoptosis, and lactate dehydrogenase (LDH) release were measured in cultured neurons. Furthermore, the levels of IL-1β and nitric oxide (NO) release were also detected in cultured microglia. The possible mechanisms for the neuroprotective effect of NSP were explored using Western blot analysis. Results: NSP administration can reverse abnormal variations in neurons and microglia-mediated inflammatory response induced by OGD/R processes. The neuronal survival rate, neuronal apoptosis rate, and LDH release were significantly improved by NSP administration in neurons. Simultaneously, the release of IL-1β and NO were significantly reduced by NSP in microglia. Western blot showed that the expression of ERK, P38, and JNK was upregulated in microglia by the OGD/R treatment, and these effects were significantly inhibited by NSP. Conclusion: These data verified the neuroprotective effects of NSP on neurons and microglia-mediated inflammatory response. Inhibition of the mitogen-activated protein kinase (MAPK) signaling pathways might play a potential role in NSP neuroprotection on microglia-mediated inflammatory response, which needs further verification.

Neuroprotective effect of neuroserpin in oxygen-glucose deprivation- and reoxygenation-treated rat astrocytes in vitro.

Neuroserpin (NSP) reportedly exerts neuroprotective effects in cerebral ischemic animal models and patients; however, the mechanism of protection is poorly understood. We thus attempted to confirm neuroprotective effects of NSP on astrocytes in the ischemic state and then explored the relative mechanisms. Astrocytes from neonatal rats were treated with oxygen-glucose deprivation (OGD) followed by reoxygenation (OGD/R). To confirm the neuroprotective effects of NSP, we measured the cell survival rate, relative lactate dehydrogenase (LDH) release; we also performed morphological methods, namely Hoechst 33342 staining and Annexin V assay. To explore the potential mechanisms of NSP, the release of nitric oxide (NO) and TNF-α related to NSP administration were measured by enzyme-linked immunosorbent assay. The proteins related to the NF-κB, ERK1/2, and PI3K/Akt pathways were investigated by Western blotting. To verify the cause-and-effect relationship between neuroprotection and the NF-κB pathway, a NF-κB pathway inhibitor sc3060 was employed to observe the effects of NSP-induced neuroprotection. We found that NSP significantly increased the cell survival rate and reduced LDH release in OGD/R-treated astrocytes. It also reduced NO/TNF-α release. Western blotting showed that the protein levels of p-IKKBα/β and P65 were upregulated by the OGD/R treatment and such effects were significantly inhibited by NSP administration. The NSP-induced inhibition could be significantly reversed by administration of the NF-κB pathway inhibitor sc3060, whereas, expressions of p-ERK1, p-ERK2, and p-AKT were upregulated by the OGD/R treatment; however, their levels were unchanged by NSP administration. Our results thus verified the neuroprotective effects of NSP in ischemic astrocytes. The potential mechanisms include inhibition of the release of NO/TNF-α and repression of the NF-κB signaling pathways. Our data also indicated that NSP has little influence on the MAPK and PI3K/Akt pathways.

Suppression of NADPH oxidase- and mitochondrion-derived superoxide by Notoginsenoside R1 protects against cerebral ischemia–reperfusion injury through estrogen receptor-dependent activation of Akt/Nrf2 pathways

Notoginsenoside R1 (NGR1) is a novel phytoestrogen that is isolated from Panax notoginseng. We have recently found that NGR1 showed neuroprotection in vitro against oxidative stress through estrogen receptor (ER)-dependent activation of Akt/Nrf2 pathways. However, whether NGR1 has neuroprotective effect against cerebral ischemia–reperfusion (I/R) injury in vivo is unknown. In this study, we used in vivo and in vitro models of cerebral I/R injury that demonstrate middle cerebral artery occlusion and reperfusion in rats, as well as oxygen–glucose deprivation followed by reoxygenation (OGD/R) in primary cortical neurons. These models were used to evaluate NGR1 neuroprotection. Three-day pretreatment with NGR1 (20 mg/kg; i.p.) significantly improved neurologic outcomes and reduced cerebral infarct volume. Pretreatment of primary cortical neurons with NGR1 (25 μM) for 24 h prevented apoptosis and oxidative stress induced by OGD/R. NGR1 inhibited apoptosis by inhibiting mitochondrial membrane potential disruption, caspase-3 activation, and DNA fragmentation. NGR1 prevented oxidative stress by suppressing NADPH oxidase- and mitochondrion-derived superoxide and inhibiting production of malondialdehyde, protein carbonyl, and 8-hydroxydeoxyguanosine in vivo and in vitro. NGR1 induced ER-dependent activation of Akt/Nrf2 pathways by increasing ERα, ERβ, phospho-Akt, phospho-GSK3β, nuclear Nrf2, and HO-1 expression in vivo and in vitro. Pretreatment with ICI-182780, LY294002, or Snpp abolished NGR1-mediated neuroprotection against oxidative stress and apoptosis in vitro. In conclusion, NGR1 showed neuroprotection against cerebral I/R injury in vivo and in vitro. The mechanism of NGR1 neuroprotection involves inhibition of NADPH oxidase activity and mitochondrial dysfunction via ER-dependent activation of Akt/Nrf2 pathways.

Neuroprotective effects of Fructus Chebulae extracts on experimental models of cerebral ischemia

ObjectiveTo investigate the neuroprotective effects of Fructus Chebulae extract using both in vivo and in vitro models of cerebral ischemia. MethodsAs an in vitro model, oxygen glucose deprivation followed by reoxygenation (OGD-R) and hydrogen peroxide (H2O2) induced cellular damage in rat pheochromocytoma (PC12) cells was used to investigate the neuroprotective effects of extract of Fructus Chebulae. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to calculate cell survival. For in vivo, occlusion of left middle cerebral artery on rats was carried out as a focal cerebral ischemic model. ResultsFructus Chebulae extract increases the PC12 cell survival against OGD-R and H2O2 by 68% and 91.4% respectively. Fructus Chebulae also decreases the cerebral infarct volume by 39% and extent of hemisphere swelling from 17% in control group to 10% in Fructus Chebulae treated group. ConclusionFructus Chebulae, as a traditional medicine, can rescue the neuronal cell death against ischemia related damage. The possible mechanism for the neuroprotection might be the inhibition of oxidative damages occurring after acute phase of cerebral ischemia.

At low doses ethanol maintains blood–brain barrier (BBB) integrity after hypoxia and reoxygenation: a brain slice study

Post-ischemia ethanol (EtOH) treatments have been shown to exhibit neuroprotective effects in stroke. However, the mechanisms underlying these effects and those on blood–brain barrier (BBB) integrity have yet to be elucidated. In the present study, we determined whether administering differing concentrations of EtOH alter the expressions of BBB integral proteins, including aquaporins-4 and -9 (AQP-4, AQP-9), matrix metallopeptidases-2 and -9 (MMP-2, MMP-9), zonula occludens-1 (ZO-1), and basal lamina (laminin).We employed an organotypic brain slice culture model that utilizes oxygen–glucose deprivation followed by reoxygenation (OGD/R). Brain slices were obtained from 10-day-old Sprague–Dawley rats and divided into the following five groups (n = 8 subjects per group): (1) control, (2) hypoxia (OGD/R), no EtOH, (3) OGD/R and 10 mM EtOH, (4) OGD/R and 30 mM EtOH, and (5) OGD/R and 90 mM EtOH. To assess BBB integrity, levels of AQPs, MMPs, ZO-1, and laminin were determined by Western blot.Compared to control, OGD/R without EtOH significantly increased AQP-4, AQP-9, MMP-2, and MMP-9 levels, while decreasing ZO-1 and laminin levels. All EtOH concentration treatments (groups 3 through 5) significantly reduced the expressions of AQP-4, AQP-9, MMP-2, and MMP-9, compared to the OGD/R, non-alcohol treated slices. Furthermore, compared to the OGD/R without EtOH group, the 30 mM EtOH treatment significantly increased ZO-1 and laminin levels. In contrast, the 90 mM EtOH level neither enhanced the reduction in AQP and MMP levels nor increased ZO-1 or basal lamina expressions observed in the 30 mM treatment.In conclusion, at an optimal dose of 30 mM, EtOH improves the expressions of MMP-2, MMP-9, AQP-4, AQP-9, ZO-1, and basal laminin, previously altered by OGD/R. These effects may indicate a beneficial effect of EtOH on BBB integrity after stroke.

Terminalia chebula Extract Protects OGD-R Induced PC12 Cell Death and Inhibits LPS Induced Microglia Activation

Terminalia chebula, native to Southeast Asia, is a popular medicinal plant in Ayurveda. It has been previously reported to have strong antioxidant and anti-inflammatory efficacy. In this study, we aimed to investigate if fruit extract from T. chebula might protect neuronal cells against ischemia and related diseases by reduction of oxidative damage and inflammation in rat pheochromocytoma cells (PC12) using in vitro oxygen-glucose deprivation followed by reoxygenation (OGD-R) ischemia and hydrogen peroxide (H2O2) induced cell death. Cell survival was evaluated by a 2-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Free radical scavenging, lipid peroxidation and nitric oxide inhibition were measured by diphenyl-1-picrylhydrazyl (DPPH), thiobarbituric acid (TBA) and Griess reagent, respectively. We found that T. chebula extract: (1) increases the survival of cells subjected to OGD-R by 68%, and H2O2 by 91.4%; (2) scavenges the DPPH free radical by 96% and decreases malondialdehyde (MDA) levels from 237.0 ± 15.2% to 93.7 ± 2.2%; (3) reduces NO production and death rate of microglia cells stimulated by lipopolysaccharide (LPS). These results suggest that T. chebula extract has the potential as a natural herbal medicine, to protect the cells from ischemic damage and the possible mechanism might be the inhibition of oxidative and inflammatory processes.